Download Absence of cellular responses to a putative autoantigen in

Absence of Cellular Responses to a Putative Autoantigen
in Onchocercal Chorioretinopathy
Cellular Autoimmunity in Onchocercal Chorioretinopathy
Philip]. Cooper *-\ Ronald H. Guderian* Roberto Proano* and David W. Taylorf
Purpose. Onchocerciasis is a major cause of blindness in the developing world. An autoimmune
pathogenesis for onchocercal chorioretinopathy was proposed after the identification of a
recombinant Onchocerca volvulus antigen (designated Ov39) demonstrated immunologic crossreactivity with a component of the retinal pigment epithelium and other ocular tissues. The
aim of this study was to determine whether patients with onchocercal chorioretinopathy have
enhanced lymphoproliferative responses to Ov39 compared to those without chorioretinal
disease.
Methods. Lymphocyte blastogenic assays were performed using peripheral blood mononuclear
cells (PBMCs) from patients with and without evidence of chorioretinopathy. PBMCs were
cultured with Ov39, and supernatant fluids from Ov39-stimulated PBMCs were used to determine levels of the cytokines, interferon-7, and interleukin-5.
Results. Lymphoproliferative responses to Ov39 were not enhanced in patients with onchocercal chorioretinopathy compared to those without clinical evidence of chorioretinal disease.
Conclusions. A role for Ov39-specific cellular autoreactivity in the pathogenesis of onchocercal
chorioretinopathy could not be demonstrated. Invest Ophthalmol Vis Sci. 1996; 37:405-412.
Unchocerciasis is a major cause of blindness in parts
of tropical Africa and Central and South America. The
parasite, Onchocerca volvulus, is a filarial nematode
transmitted by black flies of the genus Simulium, and
it infects an estimated 18 million people worldwide, of
which approximately 350,000 are blind and a similar
number are visually impaired.'
Blinding lesions may affect the anterior and posterior segments and cause sclerosing keratitis, iridocyclitis, optic atrophy, and chorioretinopathy.2 Posterior
segment lesions, particularly chorioretinopathy, account for most visual loss in this disease.3"5
The pathogenesis of chorioretinopathy is poorly
understood. Possible mechanisms include inflammaI'rom the * Department of Clinical Investigations, Hospital Vozandes, Quito,
Ecuador, and the •{Department of Pathology, University of Cambridge, United
Kingdom.
Supported \iy grants from the. British Medical Research Council, the Royal Society,
and the British Council for the Prevention of Blindness. PC was supported l/y the
British Medical Research Council and a Sadder Studentship.
Submitted for publication May 25, 1995; revised November 6, 1995; accepted
November 8, 1995.
Proprietary interest category: N.
Reprint requests: Philip Cooper, Laboratory of Parasitic Diseases, Department of
Health and Human Setvices, National Institutes of Health, Building 4, Room 126,
Bethesda, MD 20H92.
investigative Ophthalmology & Visual Science, February 1996, Vol. 37, No. 2
Copyright © Association for Research in Vision and Ophthalmology
Downloaded From: http://iovs.arvojournals.org/ on 08/11/2017
tory reactions to dead microfilariae,b 7 eosinophil-derived toxic effector molecules,8'9 immune complex disease,10 toxic secretory-excretory products of microfilariae,"12 and autoimmunity.l3~l(>
Numerous observations lend support for an autoimmune role in the pathogenesis of chorioretinopathy
in onchocerciasis. First, the epidemiologic relationship between chorioretinopathy and ocular and dermal micronlarial burdens is equivocal,17"20 unlike
other ocular lesions for which clear associations have
been demonstrated.17"21 Second, chorioretinopathy,
unlike other ocular conditions, tends to deteriorate
despite effective reductions in micronlarial burdens
by chemotherapy or vector control.322"28 Further,
studies U14'lb'29'30 have demonstrated the presence of
antiretinal autoantibodies in human infection sera,
though only two of these were able to demonstrate a
relationship between the presence of antiretinal antibodies and chorioretinopathy.1315
A mechanism by which infection with O. volvulus
might lead to the induction of autoimmunity is molecular mimicry. It has been suggested that foreign antigens that share antigenic determinants with host mole-
405
406
Investigative Ophthalmology & Visual Science, February 1996, Vol. 37, No. 2
cules might, under certain circumstances, induce
autoreactive immune responses.31 Recently, a recombinant antigen (designated Ov39) has been isolated
from an adult female 0. volvulus cDNA library that
demonstrates immunologic cross-reactivity with a 44kDa component of the retinal pigment epithelium
and other ocular tissues.1516 Because most animal
models of inflammatory uveitis32'33 and many human
uveitis diseases34"36 are thought to be mediated by autoreactive T lymphocytes, we sought to determine
whether patients with onchocercal chorioretinopathy
had enhanced lymphoproliferative responses to Ov39.
1% tropicamide and 10% phenylephrine, the ocular
fundus was examined with a Keeler (Windsor, UK)
indirect ophthalmoscope. The optic disc was examined for the presence of atrophy, papillitis, increased
pigmentation, and sheathing of the central retinal vessels. Abnormalities of the retina and choroid were
noted. Particular attention was paid to the presence of
mottling or confluent atrophy of the retinal pigment
epithelium and chorioretinal scarring with retinal pigment epithelial atrophy, pigment clumping, and/or
choriocapillary atrophy.
Antigen Preparation
MATERIALS AND METHODS
Patient and Control Groups
Patients were recruited from a hyperendemic area in
the rain forest focus of onchocerciasis in the Santiago
River Basin of Esmeraldas Province in Ecuador. The
communities living in this area included both indigenous Amerindian (Chachi tribe) and Ecuadorians of
African descent (Afro-Ecuadorians). Ethnographic
features of these communities have been described
elsewhere.37 Patients were selected from 35 villages.
Patients were brought to a central examination area
for bleeding and ocular examination.
One hundred seventeen persons infected with O.
volvulus were recruited (INF group). Selection was
based on data compiled as part of a community-based
study of the efficacy of the macrofilaricidal drug amocarzine. Detailed parasitologic and ophthalmologic information was available for each patient for a period
of at least 3 years before the start of this study. All had
received 1 to 3 annual doses of oral amocarzine, with
the last dose administered at least 6 months before
bleeding. Patients who were parasitologically positive
were selected on the basis of the presence or absence
of chorioretinopathy.
In addition, 36 controls not resident in the onchocerciasis focus were selected. They were comprised
of two groups: Quito controls (group Q, n = 12; all
worked at the Hospital Vozandes in Quito and had
never visited an endemic area) and San Lorenzo controls (group SL, n = 24; all inhabited a small town in
Esmeraldas Province where there was no transmission
of onchocerciasis). Skin snips were taken from both
iliac crests of each individual to confirm the absence
of infection. This study followed the tenets of the Declaration of Helsinki, and informed consent was obtained from all participants.
Ocular Examination
Slit lamp examination of the anterior segment and
measurement of intraocular pressures was performed
as previously described.38 After pupil dilatation with
Downloaded From: http://iovs.arvojournals.org/ on 08/11/2017
Female O. volvulus adult worms and bovine neuroretinas, obtained from a local abattoir, were ground to
powder in liquid nitrogen and resuspended in phosphate-buffered saline. After centrifugation at 55,000g
for 20 minutes, the supernatants were passed through
a 0.2-//m filter, and protein concentrations determined using a commercial kit (Pierce, Rockford, IL).
Aliquots of antigens were stored in liquid nitrogen and
used in peripheral blood mononuclear cell (PBMC)
cultures at concentrations of 10 and 50 //g/ml for O.
volvulus antigen (Ovag) and bovine retinal extract,
respectively.
Isolation of the recombinant antigen Ov39 has
already been described.15 Recombinant clones were
constructed in the expression vector pTrcHISB (Invitrogen Corporation, San Diego, CA) and transformed into Escherichia coli NM552. Expression and
affinity purification of the fusion protein were performed according to the manufacturer's instructions.
Aliquots of purified Ov39 were stored in liquid nitrogen and used in PBMC cultures in a range of concentrations from 0.2 to 200 fig/ml. Concanavalin A
(Sigma, Poole, UK) and Candida albicans (Allergon,
Stockholm, Sweden) were used at concentrations of 5
and 10 //g/ml, respectively.
Lymphocyte Proliferation and Cytokine Assays
Fifty milliliters of venous blood was drawn from the
antecubital fossa into heparinized syringes. Peripheral
blood mononuclear cells were isolated by centrifugation on lymphoprep (Pharmacia, Uppsala, Sweden).
Cells were washed twice with Iscove's modified Dulbecco's culture medium (IMDM) and plated onto 96-well,
flat-bottomed tissue culture plates (Nunc, Roskilde,
Denmark) at a density of 2 X 106 cells/ml in a volume
of 100 fi\ of IMDM culture medium (supplemented
with 10% heat-inactivated human serum from nontransfused white male donors and 2% penicillinstreptomycin (Flow, Paisley, UK)). A further 100 (A
of medium containing antigen was added. Plates were
incubated at 37°C and 5% CO2 for 3 days (for mitogen) or 6 days (for antigen). After this time, the cultures were pulsed with 0.5 fid per well of tritiated
407
Onchocercal Chorioretinopathy
TABLE l.
Age, Sex, and Race Characteristics of Study Groups
Race
Sex
Group
Age (years)
[median (range)]
Male
Female
African
Q ( n = 12)
SL (n = 24)
INF (n = 117)
35 (23-58)
28 (18-60)
41 (15-82)
6
12
66
6
12
51
20
74
Chachi
Mestizo
12
4
43
Q = Quito controls; SL = San Lorenzo controls; and INF = infected with Onchocerca volvulus.
thymidine (Amersham Lifesciences, Amersham, UK)
for 16 hours and harvested onto filter mats for subsequent scintillation counting.
Supernatant fluids from Ov39-stimulated cultures
were used to determine the levels of interferon-y and
interleukin-5. Supernatants were harvested after 5 days
of culture for both cytokines. A capture enzyme-linked
immunosorbent assay was used for detection of both
cytokines, as previously described.39 Briefly, microtiter
plates were coated with cytokine-specific antibodies
(39D10 (DNAX Research Institute, Palo Alto, CA) for
interleukin (IL)-5 or rat anti-human interferon
(IFN)y (Interferon Sciences, New Brunswick, NJ)
overnight at 4°C. Plates were washed at each step with
0.15 M NaCl plus 0.05% Tween 20. They were blocked
with 0.15 M NaCl plus 5% bovine serum albumin plus
0.05% Tween 20 for 1 hour at 37°C and then incubated with supernatant samples for 2 hours at 37°C.
The appropriate detection antibody (5A10-NIP
(DNAX Research Institute) for IL-5 or polyclonal rabbit anti-human IFNy (National Institutes of Health,
Bethesda, MD) was added, and the plates were incubated for 1 hour at 37°C. Plates were incubated with
enzyme conjugate (J4-HRP; DNAX Research Institute)
for IL-5 or goat anti-rabbit IgG-AP(Fc) (National Institutes of Health) for IFNy for 1 hour at 37°C. Then, the
plates were developed with either ABTS peroxidase
substrate (Kirkegaard and Perry Laboratories, Gaithersburg, MD) in the presence of H2O2 for IL-5 or
alkaline phosphatase substrate (Sigma, St. Louis, MO)
for IFNy. Finally, plates were read using a microtiter
plate reader (Pasteur, Innsbruck, Austria), and unTABLE 2.
Prevalence of Chorioretinal Disease
in the Study Groups
Disease Status
Normal
RPE atrophy
Chorioretinal scars
Total
SL
12
0
0
12
(100)
(0)
(0)
(100)
24
0
0
24
(100)
(0)
(0)
(100)
INF
57
22
38
117
(49)
(19)
(32)
(100)
Values are number (%). RPE = retinal pigment epithelium; Q =
Quito controls; SL = San Lorenzo controls; and INF = infected
with Onchocerca volvulus.
Downloaded From: http://iovs.arvojournals.org/ on 08/11/2017
known values were interpolated from standard curves
prepared using recombinant standards.
Statistical Analysis
Skin infection intensities are expressed as the geometric mean number of microfilariae per milligram of
skin. Comparison of proportions were analyzed using
X2 and of means using Student's <-test. Comparison
of means of more than two independent groups was
performed using one-way analysis of variance. Multiple
comparisons of group differences revealed by analysis
of variance were tested using a modified Student's ttest with the Bonferroni adjustment.40 Bivariate analysis was performed by calculation of Spearman's rank
correlation coefficients.
RESULTS
Characteristics of Patient Groups
Age, sex, and race distributions of the three study
groups are shown in Table 1. In group INF, the median ages of those with and without chorioretinopathy
were 44 and 40 years, respectively. Geometric mean
infection intensity of the INF group was 6.3 mf/mg.
Chorioretinal disease status of subjects in the three
groups is shown in Table 2.
Lymphoproliferative Responses to Mitogen, C.
albicans, and Ovag
Blastogenic responses to mitogen (concanavalin A),
Candida albicans, and Ovag are shown in Table 3. Significant responses to mitogen, nonparasite (C. albicans) , and crude adult O. volvulus antigens were seen
in all groups.
Lymphoproliferative Responses to Ov39
Blastogenic responses to Ov39 in each group are
shown in Table 3. There was significant intergroup
variation in responses (P < 0.001). There was no difference between the proliferation of the two control
groups. Responses of the two control groups combined were greater than those in all infected patients
(P < 0.001). There was no evidence of antigen recognition in the INF group overall (SI = 1.1). A similar
408
Investigative Ophthalmology & Visual Science, February 1996, Vol. 37, No. 2
TABLE 3.
Group
Q
SL
INF
Peripheral Blood Mononuclear Cell Responses
ConA
C. Albicans
Ovag
OV39
Retina
65 (42-99)
70 (45-109)
62 (53-73)
7 (4-14)
20 (14-28)
12 (8-19)
4 (2-7)
11 (7-17)
17 (14-20)
2.6 (1.6-4.2)
1.9 (1.4-2.6)
1.1 (1.0-1.3)
1.7 (1.2-2.4)
2.0 (1.6-2.4)
1.7 (1.5-1.9)
Responses are to concanavalin A (ConA), Candida albicans, Onchocerca volvulus adult worm antigen
(Ovag), the cross-reactive recombinant antigen Ov39, and retinal extract (Retina) in each group.
The geometric mean stimulation index and 95% confidence intervals (in brackets) are shown. Q =
Quito controls; SL = San Lorenzo controls; and INF = infected with 0. volvulus,
pattern was seen using a range of concentrations of
Ov39 from 0.2 //g/ml to 200 Mg/ml (data not shown).
Data were analyzed also using a responder-nonresponder dichotomy, with a responder defined as a
subject with a stimulation index to Ov39 greater than
2. The proportion of responders to Ov39 in each
group were: Q group, 67%; SL group, 46%; and INF
group, 18%.
No relationship was seen between the presence
and severity of chorioretinal disease in infected subjects and blastogenic responses to Ov39 (Fig. 1). There
were no statistically significant intergroup differences.
Chorioretinal disease was seen in eight responders,
which, as a proportion of all those with chorioretinal
disease (8/60, or 13.3%), did not differ from those
without (12/57, or 21%).
Longitudinal ophthalmologic follow-up data were
available for 41 of the 117 INF group subjects during
the previous 3 years. Subjects were defined according
to evidence for development or deterioration of
chorioretinopathy and were divided into three groups:
no clinical evidence of the development of new lesions
or deterioration of existing chorioretinopathy in either eye (type 0); evidence of development of new
chorioretinal lesions in previously unaffected individuals (type 1); and evidence of extension of existing
disease (type 2). The proportions belonging to each
category were: type 0, 37% (15/41); type 1, 37% (15/
41); and type 2, 26% (11/41). No significant intergroup proliferative responses were seen (Fig. 2).
The relationships between proliferative responses to
Ov39 and other covariates of interest are shown in
Table 4. No significant correlations were seen. No differences in proliferative responses to Ov39 were seen
between patients with and without chorioretinopathy
TypeO
Type 1
Type 2
FIGURE 2. Relationship between peripheral blood mononuclear cell responses to Ov39 and retinal extract and the
development of new chorioretinal lesions and extension of
existing lesions in subjects infected with Onchocerca volvulus
(n = 41). Types of lesions are: type 0 = no evidence of
development or deterioration of chorioretinopathy in either
Scarring
Normal
RPE atrophy
eye; type 1 = development of chorioretinal lesion in previously unaffected person; type 2 = development of new
FIGURE l. Relationship between peripheral blood mononulesion in other eye or extension of chorioretinopathy in
clear cell proliferation to Ov39 and retinal extract and
chorioretinopathy in subjects infected with Onchocerca volvu- affected eye in person with previous evidence of disease.
Clear columns denote proliferative responses to Ov39, and
lus (n = 117). Clear columns denote proliferative responses
shaded columns denote responses to retinal extract. Colto OV39, and shaded columns denote responses to retinal
umns represent geometric mean stimulation indices, and
extract. Columns represent geometric mean stimulation inbars represent 95% confidence intervals.
dices, and bars represent 95% confidence intervals.
Downloaded From: http://iovs.arvojournals.org/ on 08/11/2017
Onchocercal Chorioretinopathy
409
thermore, Ov39 was recognized (stimulation index
greater than 2) by PBMCs from only a small proportion of subjects infected with O. volvulus, and recognition was more frequent in those without the infection.
Several factors might limit the validity and generalizability of these study findings. First, amocarzine
treatment may have prevented disease evolution
through reduction of parasite burdens. This is unlikely
because a large proportion of the amocarzine-treated
sample (26/41, or 63.4%) for which longitudinal ophthalmologic data were available showed evidence of
evolving chorioretinopathy. Second, the pathoetiology of chorioretinopathy might vary between disease
foci. However, the pattern of ocular onchocerciasis
0-10
10-50
50+
and the clinical appearance and distribution of
Microfilarial intensity (mf/mg)
chorioretinal lesions seen in this focus38 are identical
to those described in West African foci, particularly in
FIGURE 3. Relationship between peripheral blood mononuclear cell responses to Ov39, chorioretinopathy, and microrain forest areas.341 Third, it could be argued that
filarial intensity. Clear columns represent proliferative reautoreactive T cells are sequestered in ocular tissues
sponses to Ov39 in subjects infected with Onchocerca volvulus and cannot be detected in assays using peripheral
without chorioretinopathy, and shaded columns denote reblood. This seems unlikely because onchocerciasis is
sponses in subjects infected with Onchocerca volvulus with a systemic infection and sensitization to the parasitechorioretinopathy. Responses in both groups are stratified
derived antigen Ov39 would occur peripherally long
according to microfilarial intensity (mf/mg). Columns repbefore
and during the development of posterior segresent geometric mean stimulation indices, and bars reprement
disease.
sent 95% confidence intervals.
The absence of a relationship between cellular
responses to Ov39 (and retinal antigen) and onchocat different levels of microfilarial intensity in the skin
ercal chorioretinopathy is significant because cellular
(Fig. 3).
immune mechanisms (here measured as PBMC blastogenesis) are thought to be of central importance in
Lymphoproliferative Responses to Retinal
the pathogenesis of autoimmune inflammatory disExtract
eases of the uvea in humans34"36 and in experimental
Blastogenic responses to bovine retinal extract are
autoimmune uveoretinitis in animal models.32'33 All
shown in Table 3. There were no significant incurrent evidence in favor of autoreactivity in onchoctergroup differences in proliferation. There was no
ercal chorioretinopathy is derived from the detection
relationship between blastogenic responses to this anof retina-specific autoantibodies in human infection
13,14,16,29,30
tigen and either chorioretinal disease status (Fig. 1)
sera.
or the development and deterioration of new lesions
The finding of an association between cellu(Fig. 2). A positive correlation was seen with black
lar42"44 and humoral45'46 responses to the two uveitoparace (Table 4).
thogenic peptides, retinal S-antigen and interphotoreceptor retinoid binding protein, and clinical disease
Cytokine Production by Ov39-Stimulated
in human uveitis has led to the suggestion of a role
Peripheral Blood Mononuclear Cells
for these proteins in the pathogenesis of chorioretinopathy in onchocerciasis.29 Though Vingtain and coProduction of IFNy and IL-5 were negligible in Ov39stimulated cultures.
TABLE 4.
DISCUSSION
There is no evidence in this study to support the hypothesis that cellular autoimmune mechanisms are
involved in the pathogenesis of chorioretinopathy in
onchocerciasis. There was no evidence of increased
cellular responsiveness to either "self (crude retinal
antigen) or the putative parasite autoantigen (Ov39)
in subjects infected with O. volvulus with chorioretinopathy compared to those without this lesion. Fur-
Downloaded From: http://iovs.arvojournals.org/ on 08/11/2017
Correlations Between Ov39 and
Retinal Antigen and Covariates of Interest
in Subjects Infected With Onchocerca
volvulus
Antigen
OV39 20
Retinal antigen
Race
Sex
Age
Al/5
0.154
-0.363*
0.108
0.119
-0.168
-0.019
-0.116
-0.108
n = 117. Test statistics are Spearman's rank correlation
coefficient. MfS = skin microfilarial intensity. *P < 0.05.
410
Investigative Ophthalmology & Visual Science, February 1996, Vol. 37, No. 2
workers18 were able to demonstrate the presence of
significantly higher levels of S-antigen antibodies in
patients with onchocerciasis with posterior pole
involvement, subsequent studies'1 have been unable
to demonstrate a similar relationship with either Santigen or interphotoreceptor retinoid binding protein. Further, cellular responses to these peptides were
similar in patients with onchocerciasis with and without chorioretinal diseases.'17
Autoantibodies with specificity for a number of
different tissues have been identified in sera from patients with onchocerciasis. These include nonorganspecific cytoplasmic and nuclear antigens,48 the calcium binding protein calreticulin,4849 elastin and collagen,50 and immunoglobulin M rheumatoid factor.31
The clinical significance of these findings is uncertain.
Detection of autoantibodies is a common finding in
healthy populations of tropical regions52 and in a
number of tropical infections.53"55 Autoantibodies
may result from polyclonal activation of T and B cells,
which is a feature of infection with parasites.56"58 Hypergammaglobulinemia is a feature of O. volvulus infection and, because 10% to 30% of B cells produce
antibodies that are able to bind autoantigens,59 selfreactivity is not an unexpected finding.
DNA:DNA hybridization studies have demonstrated Ov39-homologous sequences in other nematodes, including other Onchocerca spp, Loa loa, and
Brugia malayi.b0 It is likely that other nematodes, including intestinal parasites, share homologous sequences. This might explain the apparent recognition
of Ov39 in the control groups.
The mechanism most likely to account for the
initiation of retinal pathology is bystander damage resulting from inflammation directed against dead and
degenerating microfilariae. Microfilariae have been
demonstrated in the retina in vivo3'60'61 and histologically/1'7 The relationship between treatment with microfilaricides and the induction of characteristic retinal pathology24 is strong evidence in support. However, the incidence of new lesions after chemotherapy
is extremely low, whereas the extension of existing
disease is common.2728 Further, the development of
new lesions is correlated with microfilarial burdens in
the Ecuadorian focus, whereas the extension of existing disease is not (Cooper et al, unpublished data,
1995). These observations suggest that, though
chorioretinopathy is likely to be initiated by the presence of microfilariae, disease extension no longer requires their presence. The induction of pathology
might set off self-perpetuating autoimmune processes
that no longer require the presence of microfilariae.
Key Wards
autoimmunity, chorioretinopathy, Ecuador, filariasis, onchocerciasis
Downloaded From: http://iovs.arvojournals.org/ on 08/11/2017
Acknowledgments
The authors thank personnel at Keeler Ltd. for the loan of
an indirect ophthalmoscope and the British Council for the
Prevention of Blindness for a grant to purchase it; Gabi
Braun and Tom Nutman for kindly providing the OV39
recombinant clone and cytokine enzyme-linked immunosorbent assay reagents, respectively; Gabi Ayovi, Manuel Anapa,
and Inocencia Ballesteros for expert assistance in the field;
and the communities living along the Rio Cayapas and the
inhabitants of San Lorenzo for their cooperation.
References
1. World Health Organisation Expert Committee on Onchocerciasis. Third report. Technical Report Series.
1987; 752.
2. Thylefors B. Ocular onchocerciasis. Bull WHO.
1978;56:63-78.
3. Semba RD, Murphy RP, Newland HS, Awadzi K,
Greene BM, Taylor HR. Longitudinal study of lesions
of the posterior segment in onchocerciasis. Ophthalmology. 1990;97:1334-1341.
4. Newland HS, White AT, Greene BM, Murphy RP, Taylor HR. Ocular manifestations of onchocerciasis in a
rain forest area of West Africa. Br J Ophthalmol.
1991;75:163-169.
5. Abiose A, Murdoch I, Babalola O, et al. Distribution
and aetiology of blindness and visual impairment in
mesoendemic onchocercal communities, Kaduna
State, Nigeria. Br J Ophthalmol. 1994; 78:8-13.
6. Rodger FC. The pathogenesis and pathology of ocular
onchocerciasis: IV: The Pathology. Am J Ophthalmol.
1960; 49:560-594.
7. Neumann E, Gunders AE. Pathogenesis of the posterior segment lesion of ocular onchocerciasis. AmJ Ophthalmol. 1973; 75:82-89.
8. John T, Barsky H, Donnelly JJ, Rockey JH. Retinal
pigment epitheliopathy and neuroretinal degeneration in ascarid-infected eyes. Invest Ophthalmol Vis Sci.
1986;28:1583-1598.
9. Semba RD, Donnelly JJ, Young E, Green WR, Scott
AL, Taylor HR. Experimental ocular onchocerciasis
in cynomolgus monkeys: IV: Chorioretinitis elicited
by Onchocerca volvulus microfilariae. Invest Ophthalmol
Vis Sci. 1991;32:1499-1507.
10. Greene BM, Taylor HR, Brown EJ, Humphrey RL,
Lawley TJ. Ocular and systemic complications of diethylcarbamazine therapy for onchocerciasis: association
with circulating immune complexes. / Infect Dis.
1983; 147:890-897.
11. Bryant J. Endemic retino-choroiditis in the AngloEgyptian and its possible relationship to Onchocerca
volvulus. Trans R Soc Trap Med Hyg. 1935; 28:523-532.
12. Garner A, Duke BOL. Fundus lesions in the rabbit
eye following inoculation of Onchocerca volvulus microfilariae into the posterior segment. Trop MedParasitol. 1976;27:19-29.
13. Vingtain P, Thillaye B, Karpouzas I, Faure JP. Longitudinal study of microfilarial infestation and humoral
immune response to filarial and retinal antigens in
Onchocercal Chorioretinopathy
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
onchocerciasis patients treated with ivermectin. Oph28.
thalmic Res. 1988; 20:95. Abstract.
Van der Lelij A, Doekes G, Hwan BS, et al. Humoral
autoimmune response against S-antigen and IRBP in
ocular onchocerciasis. Invest Ophthalmol Vis Sci.
29.
1990;31:1374-1380.
Braun G, McKechnie NM, Connor V, et al. Immunological crossreactivity between a cloned antigen of Onchocerca volvulus and a component of the retinal pig- 30.
ment epithelium. J Exp Med. 1991;174:169-177.
McKechnie NM, Braun G, Connor V, et al. Immunologic cross-reactivity in the pathogenesis of ocular onchocerciasis. Invest Ophthalmol Vis Sci. 1993; 34:2888- 31.
2902.
Anderson J, Fuglsang H, Marshall TF de C, Radolowicz
32.
A, Vaughan JP. Studies on onchocerciasis in the
United Cameroon Republic: IV: A four-year follow-up
of six rain-forest and six savanna villages. The inci33.
dence of ocular lesions. Trans R Soc Trop Med Hyg.
1978; 72:513-515.
McMahon JE, Sowa SIC, Maude GH, Kirkwood BR.
Onchocerciasis in Sierra Leone 3: Relationships be34.
tween eye lesions and microfilarial prevalence and intensity. Trans R Soc Trop Med Hyg. 1988;82:601-605.
Dadzie KY, Remme J, Rolland A, Thylefors B. Ocular
onchocerciasis and intensity of infection in the com35.
munity. 11. West African rain forest foci of the vector
Simuliumyahense. Trop Med Parasitol. 1989; 40:348-354.
Dadzie KY, Remme J, Baker RHA, Rolland A, Thylef36.
ors B. Ocular onchocerciasis and intensity of infection
in the community. 111. West African rain forest foci
of the vector Simulium sanctipauli. Trop Med Parasitol.
37.
1990;41:376-382.
Remme J, Dadzie KY, Rolland A, Thylefors B. Ocular
onchocerciasis and intensity of infection in the community. 1. West African savanna. Trop Med Parasitol.
38.
1989; 40:340-347.
Anderson J, Fuglsang H, Marshall TF de C. Effects of
diethylcarbamazine on ocular onchocerciasis. Tropenmed Parasitol. 1976;27:263-278.
39.
Anderson J, Fuglsang H, Marshall TF de C. Effects of
suramin on ocular onchocerciasis. Tropenmed Parasitol.
1976; 27:279-296.
Bird AC, El Sheikh H, Anderson J, Fuglsang H.
40.
Changes in visual function and in the posterior segment of the eye during treatment of onchocerciasis
41.
with diethylcarbamazine citrate. Br J Ophthalmol.
1980;64:191-200.
Dadzie KY, Remme J, De Sole G. Epidemiological im42.
pact of vector control: II: Changes in ocular onchocerciasis. Ada Leidensa. 1990; 59:127-139.
Dadzie KY, Remme J, Alley ES, de Sole G. Changes in
ocular onchocerciasis four and twelve months after
43.
community-based treatment with ivermectin in a holoendemic onchocerciasis focus. Trans R Soc Trop Med
Hyg. 1990;84:103-108.
Rothova A, Van der Lelij A, Stilma JS, Klaassen44.
Broekema N, Wilson WR, Barbe RF. Ocular involvement in patients with onchocerciasis after repeated
treatment with ivermectin. Am J Ophthalmol. 1990;
110:6-16.
45.
Downloaded From: http://iovs.arvojournals.org/ on 08/11/2017
411
World Health Organisation. The effect of repeated
ivermectin treatment on ocular onchocerciasis: Report of an informal consultation. TDR/TDE/ONCHO.
1993;4-5.
Chan CC, Nussenblatt RB, Kim MK, Palestine AG,
Awadzi K, Ottesen EA. Immunopathology of ocular
onchocerciasis 2: Anti-retinal autoantibodies in serum
and ocular fluids. Ophthalmology. 1987;94:439-443.
Zhou Y, Dziak E, Unnasch TR, Opas M. Major retinal
cell components recognised by onchocerciasis sera are
associated with the cell surface and nucleoli. Invest
Ophthalmol Vis Sci. 1994;355:1089-1099.
Oldstone MBA. Molecular mimicry and autoimmune
disease. Cell. 1987; 50:819-820.
Caspi RR, Roberge FG, McAllister CG, et al. T cell
line mediating experimental autoimmune uveoretinitis (EAU) in rats. J Immunol. 1986; 136:928-933.
Caspi RR. Basic mechanisms in immune-mediated
uveitic disease. In: Lightman S, ed. Immunology of Eye
Diseases. Amsterdam: Kluwer Academic Publishers;
1989:61-86.
Lightman SL, Chan CC. Immunopathology of ocular
inflammatory disorders. In: Lightman S, ed. Immunology of Eye Diseases. Amsterdam: Kluwer Academic Publishers; 1989:87-99.
Detrick B, Hooks JJ. Autoimmune aspects of ocular
disease. In: Rose NR, ed. The autoimmune diseases II.
London: Academic Press; 1992;345-361.
Forrester JV. New concepts on the role of autoimmunity in the pathogenesis of uveitis. Eye. 1992; 6:433446.
Guderian RH, Leon LA, Leon R, Corral F, Vasconez
C, Johnston TS. Report on a focus of onchocerciasis
of Esmeraldas province of Ecuador. Am J Trop Med
Hyg. 1982; 31:270-274.
Cooper PJ, Proano R, Beltran C, Anselmi M, Guderian
RH. Onchocerciasis in Ecuador: Ocular findings in
Onchocerca volvulus infected individuals. Br J Ophthalmol. 1995; 79:157-162.
Steel C, Lujan-Trangay A, Gonzalez-Peralta C, ZeaFlores G, Nutman TB. Transient changes in cytokine
profiles following ivermectin treatment of onchocerciasis. / Infect Dis. 1994; 170:962-970.
Altman DG. Practical statistics for medical research.
London: Chapman and Hall; 1991:210-212.
Bird AC, Anderson J, Fuglsang H. Morphology of posterior segment lesions of the eye in patients with onchocerciasis. BrJ Ophthalmol. 1976;60:2-20.
Nussenblatt RB, Mittal KK, Ryan S, Green WR, Maumenee AE. Birdshot retinochoroidopathy: An association with HLA-A29 and immune responsiveness to retinal S-antigen. Am J Ophthalmol. 1982;94:147-158.
Doekes G, Van der Gaag R, Rothova A, et al. Humoral
and cellular immune responsiveness to human S-antigen in uveitis. Curr Eye Res. 1987; 7:909-919.
De Smet MD, Mochizuki M, Gery I, et al. Cellular
immune responses of patients with uveitis to retinal
antigens and their fragments. Am J Ophthalmol.
1991;110:135-142.
Gregerson DS, Abrahams IW, Thirkill CE. Serum anti-
Investigative Ophthalmology & Visual Science, February 1996, Vol. 37, No. 2
412
46.
47.
48.
49.
50.
51.
52.
53.
body levels of uveitis patients to bovine retinal antigens. Invest Ophthalmol Vis Sci. 1981; 21:669-680.
Abrahams IW, Gregerson DS. Longitudinal study of
serum antibody responses to bovine retinal S-antigen
in endogenous granulomatous uveitis. BrJ Ophthalmol.
1983; 67:681-684.
Van der Lelij A, Rothova A, Stilma JS, Hoekzema R,
Kijlstra A. Cell-mediated immunity against human retinal extract, S-antigen, and interphotoreceptor retinoid-binding protein in onchocercal chorioretinopathy. Invest Ophthalmol Vis Sci. 1990;31:2031-3036.
Meilof JF, Van der Lelij A, Rokeach LA, Hoch SO,
Smeenk RJT. Autoimmunity and filariasis: Autoantibodies against cytoplasmic cellular proteins in sera of
patients with onchocerciasis. / Immunol. 1993;
151:5800-5809.
Rokeach LA, Zimmerman PA, Unnasch TR. Epitopes
of the Onchocerca volvulus RALl antigen, a member of
the calreticulin family of proteins, recognised by sera
from patients with onchocerciasis. Infect Immun.
1994; 62:3696-3704.
Petralanda I, Piessens WF. Pathogenesis of onchocercal dermatitis: Possible role of parasite proteases and
autoantibodies to extracellular matrix proteins. Exp
Parasitol. 1994; 79:177-186.
Kawabata M, Flores GZ, Izui S, Kobayakawa T. IgM
rheumatoid factors in Guatemalan onchocerciasis.
Trans R Soc Trop Med Hyg. 1984; 78:356-358.
Greenwood BM, Whitde HC. Immunology of Medicine
in the Tropics. London: Edward Arnold; 1981:56-58.
Greenwood BM, Herrick EM, Holborow ET. Speckled
Downloaded From: http://iovs.arvojournals.org/ on 08/11/2017
54.
55.
56.
57.
58.
59.
60.
61.
antinuclear factor in African sera. Clin Exp Immunol.
1970; 7:75-83.
Thomas MAB, Frampton G, Isenberg DA, Shoenfeld Y,
Akinsola A, Ramzy M. A common anti-DNA antibody
idiotype and antiphospholipid antibodies in sera from
patients with schistosomiasis and filariasis with and without nephritis. J Autoimmunity. 1989; 2:803-811.
Adebajo AO, Charles P, Maini RN, Hazleman BL. Autoantibodies in malaria, tuberculosis and hepatitis B
in a West African population. Clin Exp Immunol.
1993;92:73-76.
Kobayakawa T, Loius J, Izui S, Lambert PH. Autoimmune response to DNA, red blood cells and thymocyte
antigens in association with polyclonal antibody synthesis during experimental African trypanosomiasis. /
Immunol. 1979; 122:296-301.
Terry RJ, Hudson KM, Faghihi-Shirazi M. Polyclonal
activation by parasites. In: Van den Bossche H, ed. The
host-invader interplay. Proceedings 3rd International
Symposium Biochemistry Parasites and Host-Parasite
Relationships. Amsterdam: Elsevier; 1980:259-271.
Rocken M, Shevach EM. Do parasitic infections break
T-cell tolerance and trigger autoimmune disease. Parasitol Today. 1993; 9:377-380.
Tomer Y, Shoenfeld Y. The significance of natural
autoantibodies. Immunol Invest. 1988; 17:389-424.
Murphy RP, Taylor H, Greene BM. Chorioretinal damage
in onchocerciasis. Amf Ophthalmol 1984;98:519-520.
Taylor HR, Murphy RP, Newland HS, et al. Treatment
of onchocerciasis: The ocular effects of ivermectin and
diethylcarbamazine. Arch Ophthalmol 1986;104:863-870.