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Letters to the Editor
Cellular and humoral aberrations in a kindred
with IL-1 receptor–associated kinase 4
deficiency
To the Editor:
Patients who had life-threatening invasive bacterial
infections were found to have diminished ability to
respond to LPS stimulation in vitro.1,2 The defect has
been subsequently identified to be associated with mutations in the IL-1 receptor–associated kinase 4 gene
(IRAK4).3,4
IRAK-4 plays a critical role in the intracellular signaling pathway, which begins with Toll-like receptors and
IL-1 receptor and stimulates nuclear factor kB and mitogen-activated protein kinase pathways and subsequent
inflammatory cascades.5 Among the consequences of
IRAK-4 deficiency is a significant reduction in inflammatory responses to infection,6 reduced antibody responses
to polysaccharide antigens,7,8 and neutropenia.1,3,4,9
These effects explain, at least in part, the susceptibility
to bacterial infections observed in these patients. The
microbial pathogens first and most frequently identified
in IRAK-4 deficiency were Staphylococcus aureus and
Streptococcus pneumoniae.1,3,9 Indeed, most invasive infections in the 3 siblings described here were caused by
these organisms.
Patient 1 was the older sister of the twins patients 2 and
3. She was born to nonconsanguineous parents of English
descent. At the age of 5 months, she died of shock after
S aureus–induced meningitis. Patient 2, her 27-year-old
male sibling, had S pneumoniae–induced meningitis at
age 2 years, and at 5 years, he had a life-threatening episode of necrotizing epiglottitis caused by Pseudomonas
aeruginosa. Patient 3, his 27-year-old twin brother, had
meningitis at the age of 10 months, septic arthritis at 2
years, bilateral tonsillar abscesses at 6 years, a brain abscess at 8 years, and multiple abdominal abscesses at 14
years. In all episodes but one, aspiration cultures grew S
pneumoniae. At age 15 years, he had a suspected infection
with Mycobacterium avium, which was detected in blood
cultures. A subsequent computed tomographic scan of his
chest demonstrated a lesion in his right middle lobe, which
was suspicious as a possible calcified granuloma. This
does not appear to be related to abnormal IL-12 or IFN-g
because sequence analysis of relevant genes was normal.
During these episodes of recurrent invasive infection,
patients 2 and 3 demonstrated delayed, atypical, or
attenuated signs of inflammation, such as absence of fever.
Since the age of 4 years, patients 2 and 3 were given
trimethoprim-sulfamethoxazole prophylaxis, which could
not prevent severe infections. Intravenous immunoglobulin was therefore added to the regimen of infection
prevention. Interestingly, as long as patients were kept
on both modalities of treatment, they were free of infection. By the age of 18 years, both patients had stopped
taking trimethoprim-sulfamethoxazole and dropped out of
intravenous immunoglobulin therapy. Surprisingly, no
significant infections were recorded since that time for
more than a decade.
The nature of pyogenic infections and their severity
suggested IRAK-4 deficiency. Indeed, sequence analysis
of both patients revealed a homozygous C to T transition at
nucleotide 877 within exon 8 of the IRAK4 gene. This mutation created a premature stop codon at amino acid
293 (Q293X). Both parents were heterozygous for this
mutation.
Analysis of the innate immunity showed that patient 2
and patient 3’s whole-blood cells stimulated with LPS or
heat-killed S aureus failed to produce IL-6. Similarly, IL-6
production in response to IL-1b was also significantly
reduced when compared with control samples (Fig 1). In
addition, the neutrophil count ranged from 500 to 2000
cells/mm3 and 600 to 1800 cells/mm3 in patients 2 and 3,
respectively (Table I).9,10 These results are similar to those
in previously reported cases of IRAK-4 deficiency.1,3,4,9
Letters to the Editor
FIG 1. Cytokine assays. IL-6 and IL-10 production in the supernatants of cultured whole blood cells from 2
healthy control subjects (C), patient 2, and patient 3 treated with IL-1b, LPS, S aureus cowan (SAC), TNF-a, or
phorbol 12-myristate 13-acetate (PMA)–ionomycin, as measured by means of ELISA, are shown. The results
are normalized for leukocyte count.
948
Letters to the Editor 949
J ALLERGY CLIN IMMUNOL
VOLUME 120, NUMBER 4
TABLE I. Immune evaluation of patients 2 and 3
Serum Ig (g/L)
IgG
IgM
IgA
Specific antibodies
Measles (IU/mL)
Tetanus (IU/mL)
Isohemaglutinin
(anti-A)
Lymphocyte markers
(cells/mL)*
CD3
CD4
CD8
CD19
CD56
Mitogenic and antigenic
responsesà
PHA
Candida species
Tetanus
Herpes zoster
Herpes simplex
CMV
Polymorphonuclear
cells (1026/L)
Normal
range
and/or
control
Patient 2
Patient 3
15
1.3
0.3
13
1.5
0.6
7.2-15.8
0.2-3.1
0.5-3.5
1245
0.34
1:16
745
0.46
1:16
>50
>0.04
>1:8
670
455
150
267
153
745
431
200
245
106
220-2390 830-1380
480-840
220-750
30-300
577
7.2
0.5
3.8
1.5
3.6
1.7
990
19
1
20
3.1
6.1
1.5
847
>20/85
>20/23
>20/80
>20/166
>20/200
2.00-7.50
*Median value of 6 determinations obtained over 20 years.
Range of median values as determined by age group from 2 to
39 years.9,10
àStimulation index.
In conclusion, careful examination of cellular immunity
in patients with IRAK-4 deficiency showed, for the first
time, persistent lymphopenia, incomplete T-cell repertoire, and a reduced ability to respond to antigenic
stimulation in vitro. It therefore appears that in the absence
of IRAK-4, signal transduction through the Toll-like
FIG 2. TCR Vb distribution in patients 2 (P2) and 3 (P3), with absence of Vb family 7.2 in both patients.
Letters to the Editor
However, unlike previously reported cases, analysis of
cellular immunity revealed reduced numbers of CD31
cells, which either expressed CD8 or CD4. Over a period
of 20 years (as well as the most recent assessment in 2006),
CD31 cells fluctuated between 650 and 896 cells/mL
(patient 2) and 740 and 1050 cells/mL (patient 3). Recent
evaluation of T-cell response to the mitogen PHA was
comparable with the control value in patient 3 but was
only half of the control value in patient 2. Interestingly,
in vitro proliferative responses to antigens were decreased
to all 5 antigens in patient 2 and to 3 of 5 antigens in
patient 3.
These abnormalities might reflect a limited T-cell
repertoire. We therefore evaluated T-cell repertoire by
studying T-cell receptor Vb families. Surprisingly, the
analysis showed that both patients had underrepresentation
of Vb7, suggesting incomplete T-cell diversity (Fig 2).
To better define thymic function in these patients, we
have recently assessed T-cell receptor excision circles and
showed that patient 2 also had a borderline low level of Tcell receptor excision circles at 226 copies per 0.5 mg of
DNA, whereas patient 3 had a normal level of 1225 copies
per 0.5 mg of DNA (normal range, 308-2078 copies/0.5
mg of DNA). These results are consistent with patient 2’s
lower numbers of circulating CD31 cells than patient 3.
Similarly, in vitro T-cell responses to mitogens, as well
as to antigens, were inferior in patient 2 compared with
those in patient 3.
Evaluation of the humoral immune system revealed that
serum levels of IgG and IgM have always been normal in
both patients, but IgA levels were consistently reduced in
the past. Recent assessment showed a low level in patient 2
but a normal level in patient 3. Antibody titers in response
to routine immunizations (T cell–dependent protein antigens) were normal for poliovirus; measles, mumps, and
rubella viruses; and tetanus toxoid. In contrast, antipolysaccharide antibody responses to (T cell–independent) pneumococcal vaccine were markedly lower than
control responses for serotypes 3 (a strong immunogen), 4
(an intermediate immunogen), and 9N (a weak immunogen) in both boys.
950 Letters to the Editor
J ALLERGY CLIN IMMUNOL
OCTOBER 2007
receptors, as well as the T-cell receptor, might be impaired, leading to defects in both the innate and the adaptive immune systems.
Elana Lavine, MDa
Raz Somech, MD, PhDa
Jun Yan Zhanga
Anne Puel, PhDb
Xavier Bossuyt, MD, PhDc
Capucine Picard, MD, PhDb
Jean Laurent Casanova, MD, PhDb
Chaim M. Roifman, MDa
From athe Division of Immunology and Allergy, the Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada; bthe Laboratory of Human Genetics of Infectious Diseases, University of Paris
René Descartes, INSERM U550, and Pediatric Immunology-Hematology,
Necker Medical School, Paris, France; and cExperimental Laboratory Medicine, University Hospital Leuven, Leuven, Belgium.
Disclosure of potential conflict of interest: The authors have declared that they
have no conflict of interest.
REFERENCES
1. Kuhns DB, Long Priel DA, Gallin JI. Endotoxin and IL-1 hyporesponsiveness in a patient with recurrent bacterial infections. J Immunol
1997;158:3959-64.
2. Haraguchi S, Day NK, Nelson RP, Emmanuel P, Duplantier JE, Christodoulou CS, et al. Interleukin 12 deficiency associated with recurrent
infections. Proc Natl Acad Sci USA 1998;95:13125-9.
3. Picard C, Puel A, Bonnet M, Ku CL, Bustamante J, Yang K, et al.
Pyogenic bacterial infections in humans with IRAK-4 deficiency. Science
2003;299:2076-9.
4. Medvedev AE, Lentschat A, Kuhns DB, Blanco JC, Salkowski C, Zhang
S, et al. Distinct mutations in IRAK-4 confer hyporesponsiveness to
lipopolysaccharide and interleukin-1 in a patient with recurrent bacterial
infections. J Exp Med 2003;198:521-31.
5. Li S, Strelow A, Fontana EJ, Wesche H. IRAK-4: a novel member of the
IRAK family with the properties of an IRAK-kinase. Proc Natl Acad Sci
U S A 2002;99:5567-72.
6. von Bernuth H, Puel A, Ku CL. Septicemia without sepsis: inherited
disorders of nuclear factor-kB-mediated inflammation. Clin Infect Dis
2005;41(suppl):S436-9.
7. Day N, Tangsinmankong N, Ochs H, Rucker R, Picard C, Casanova JL,
et al. Interleukin receptor-associated kinase (IRAK-4) deficiency associated with bacterial infections and failure to sustain antibody responses.
J Pediatr 2004;144:524-46.
8. Ku CL, Picard C, Erdös M, Jeurissen A, Bustamante J, Puel A, et al.
IRAK4 and NEMO mutations in otherwise healthy children with recurrent invasive pneumococcal disease. J Med Genet 2007;44:16-23.
9. Shearer WT, Rosenblatt HM, Gelman RS, Oyomopito R, Plaeger S,
Stiehm ER, et al. Lymphocyte subsets in healthy children from birth
through 18 years of age: the Pediatric AIDS Clinical Trials Group
P1009 study. J Allergy Clin Immunol 2003;112:973-80.
10. McNerlan SE, Alexander HD, Rea IM. Age related reference intervals for
lymphocyte subsets in whole blood of healthy individuals. Scand J Clin
Lab Invest 1999;59:89-92.
Available online June 4, 2007.
doi:10.1016/j.jaci.2007.04.038
Letters to the Editor
Successful haploidentical bone marrow
transplantation in a patient with reticular
dysgenesis: Three-year follow-up
To the Editor:
Reticular dysgenesis (RD) is a rare form of severe
combined immune deficiency (SCID) that presents earlier
with failure to thrive, vomiting, diarrhea, and/or localized
FIG 1. Pretransplantation and posttransplantation bone marrow
cellularity. Initial bone marrow aspirate (left, 360 magnification)
shows hypocellular marrow with erythroid precursors, rare myeloid
precursors, and scattered maturing lymphocytes and macrophages.
At right, bone marrow aspirate (34 and 350 magnification) and a biopsy specimen (340 magnification) show normocellular marrow
with myeloid hypoplasia, normal erythroid and megakaryocyte maturation, and increased numbers of maturing lymphocytes.
infection. Leukopenia and neutropenia unresponsive to
granulocyte colony-stimulating factor are hallmarks, and
the clinical course is rapidly fatal without intervention.
These patients must be identified before transplantation
because successful engraftment requires conditioning. We
report a case of a successful haploidentical transplantation
in a patient with RD. This patient was conditioned with
busulfan, cyclophosphamide, and antithymocyte globulin.
The patient is now 3 years from transplantation and has
complete hematopoietic and immunologic reconstitution.
RD, first described in 1959 in male twins by Devaal and
Seynhaeve1 is one of the most unusual and rapidly progressive forms of SCID, accounting for less than 1% of
cases.2 A deficiency of granulocyte precursors in the
bone marrow, likely caused by a block in myeloid differentiation, is observed in RD. The pathogenesis is unknown; however, a defect that affects both lymphoid
and myeloid precursors is presumed. Patients characteristically demonstrate marked leukopenia and a dysplastic
thymus. Other manifestations can include thrombocytopenia and sensory deafness.3
In X-linked SCID successful transplantations without conditioning result in T-lymphocyte engraftment.
However, in RD successful bone marrow transplantations
seem to require intensive conditioning.4 In one case series
of 10 patients who received HLA-nonidentical bone marrow transplantations for RD, 5 received myeloablative
conditioning therapy with busulfan and cyclophosphamide, and of these, 3 are alive and well. The other 5
who received alternate conditioning regimens or no conditioning did not survive.4 Therefore differentiating these
patients from those with other types of SCID is necessary
to ensure optimal therapy.
Our patient presented to his pediatrician at 5 days of
life with increased sleepiness and a rectal temperature of
1048F. Initial laboratory studies revealed a white blood
cell count of 300 cells/mL and an absolute neutrophil
count (ANC) of 0 cells/mL. Blood, urine, and cerebrospinal fluid cultures were obtained, and treatment with
ampicillin, gentamicin, and acyclovir was initiated. He
remained febrile and neutropenic despite treatment with
granulocyte colony-stimulating factor. On day of life 8, he
was transferred to the Children’s Hospital of Philadelphia
for additional evaluation and therapy.