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206
T Lymphocytes in Human Atherosclerotic
Plaques Are Memory Cells Expressing
CD45RO and the Integrin VLA-1
Sten Stemme, Jan Holm, and Goran K. Hansson
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The cellular composition of human atherosclerotic plaques has been analyzed in several
immunohistochemical studies in recent years. These studies have shown that the main cell
types of the plaque are macrophages, smooth muscle cells, and T lymphocytes. To further
characterize the T-lymphocyte population in atherosclerotic plaques, human plaque tissue was
digested enzymatically and the released cells were labeled with fluorescent antibodies and
analyzed by flow cytometry. Fifteen patients undergoing carotid endarterectomy were studied.
Sixty-four percent of plaque T cells expressed the low-molecular-weight form (CD45RO) of the
leukocyte common antigen (CD45). Many of these cells expressed the integrin very late
activation antigen-1 (VLA-1), which suggests that they are in a state of late activation. In
contrast, only 1% of peripheral blood T cells from the same patients expressed VLA-1. Other
markers of T cell activation, such as Tal (CD26) and HLA-DR, were also increased on plaque
T cells. The interleukin-2 receptor (CD25), which is transiently expressed after activation, was
present on only a small proportion of the cells. Taken together, this analysis of plaque
lymphocytes shows that the majority of plaque T cells are memory cells, many of which are in
a state of late or chronic activation. This T-cell phenotype may be the result of a preferential
recruitment and/or retention of activated peripheral blood T cells or local antigenic stimulation
of resting T cells. (Arteriosclerosis and Thrombosis 1992;12:206-211)
he main cell types in human atherosclerotic
lesions are macrophages, smooth muscle
cells, and T lymphocytes.1-2 The presence of
T lymphocytes in the early stages of atherogenesis,
such as intimal thickening and fatty streaks,2-4 indicates a potential role for cellular immune mechanisms in early atherogenesis. The finding that many
of these T cells express surface antigens such as
HLA-DR and very late activation antigen-1 (VLAl)3-5 suggests that they are in an activated state and
may secrete cytokines that can affect surrounding
vascular cells.6-7
Only previously activated T cells would be expected to participate in interactions with other cell
types, as resting T cells constitute a relatively inert
cell population with low production of lymphokines.
In addition, the pattern of lymphokine secretion is
T
distinctly different in T cells activated by recall
antigens compared with that of naive T cells activated for the first time.8 It is therefore important to
establish the proportion of previously activated T
cells in atherosclerotic lesions and their current state
of activation.
Previous studies have used immunohistochemistry
to characterize plaque cell composition and phenotype. These investigations have, however, been restricted by the limitations of immunohistochemical
techniques. In the present study, we have used flow
cytometry, which facilitates double labeling and quantification of surface antigen expression. Our results
indicate that the majority of T lymphocytes in human
atherosclerotic plaques are memory cells, many of
which are in a state of late or chronic activation.
From the Departments of Clinical Chemistry (S.S., G.K.H.) and
Surgery (J.H.), Gothenburg University, Gothenburg, Sweden.
Supported by the Swedish Medical Research Council (project
No. 6816), the Swedish Heart-Lung Foundation, The Swedish
Stroke Fund, the Gothenburg Medical Society, and research funds
of Gothenburg University.
Address for correspondence: Sten Stemme, Department of
Clinical Chemistry, Sahlgren's Hospital, Gothenburg University,
S-413 45 Gothenburg, Sweden.
Received July 30, 1991; revision accepted October 17, 1991.
Cell Isolation
Methods
Atherosclerotic plaques were obtained from 15
patients, 12 men and three women, between 52 and
77 years of age, who were undergoing carotid endarterectomy for transient ischemic attacks. None of the
patients suffered from any known chronic inflammatory disease. The specimens represented advanced
lesions, usually involving most of the arterial circum-
Stemme et al Flow Cytometric Analysis of Plaque T Cells
TABLE 1. Antibodies Used in the Study
Specificity
Supplier
•CD25
HLA-DR
CD26
al-subunit, CD49a
CD45RA
CD45RO
BD
CD3
BD
CD8
CD4
BD
a^TCR
S-Chain of TCR
BD
Antibody
Anti-IL-2R
Anti-HLA-DR
Tal
VLA-1 (TS2/7)
2H4
UCHL1
Leu-4
Leu-2a
Leu-3a
TCR-1 (WT31)
TCR51
Control mouse IgG
BD
C
T
C
D
BD
T
C
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IL-2R, interleukin-2 receptor; VLA-1, very late activation antigen-1; IgG, immunoglobulin G; 'CD, cluster of differentiation; BD,
Becton Dickinson, Mountain View, Calif.; C, Coulter Immunology,
Hialeah, Fla.; T, T Cell Sciences, Cambridge, Mass.; D, Dakopatts,
Glostrup, Denmark.
ference, and were often complicated with calcification or ulceration.
Cells were isolated essentially as described.7 In
brief, tissue specimens consisting of the plaque and
inner media were meticulously cleared of peripheral
blood and any thrombotic material. To destroy lymphocytes that might remain adherent to the surface,
the plaque was washed four times in 20 ml distilled
water. The tissue was then minced into fine pieces
and digested for 3 hours at 37°C with collagenase
type I (Sigma Chemical Co., St. Louis, Mo.) at 900
units/ml in phosphate-buffered saline (PBS) with 5
mg/ml bovine serum albumin (radioimmunoassay
grade, Sigma), 0.2 mM CaCl2, and 1 mg/ml glucose.
The resulting cell suspension was filtered through a
150-mesh nylon net, washed in PBS, and stained for
flow cytometry. Peripheral blood mononuclear cells
from the patients and healthy blood donors were
isolated by Ficoll-Paque (Pharmacia, Uppsala, Sweden) gradient centrifugation.
Flow Cytometry
Cells were incubated with antibodies at previously
determined optimal concentrations at 4°C for 30 minutes and washed once in PBS between steps. The
antibodies used are listed in Table 1. After a final
wash in PBS, the cells were fixed with 1% paraformaldehyde in PBS and analyzed in a Becton Dickinson
FACScan flow cytometer (Becton Dickinson, Mountain View, Calif.).
For determination of their state of activation, T
cells were double-labeled with phycoerythrin-conjugated Leu-4 (anti-CD3) and one of a panel of
fluorescein isothiocyanate (FITC)-labeled monoclonal antibodies (MAbs). When unconjugated MAbs
were used, cells were incubated with the primary
MAb, followed by staining with a secondary FITClabeled goat anti-mouse immunoglobulin G (Becton
Dickinson). The proportion of positive cells was
207
determined among the CD3-positive cells. To classify
cells as positive or negative, a threshold level was set
for each antigen and then used throughout the study.
For CD45RO and CD45RA, the level was set between that of the two populations (with high and low
expression) occurring in peripheral blood. The level
for HLA-DR-positive cells was set just below the
fluorescence intensity of monocytes in peripheral
blood. The level of CD26-positive cells was set to
include the population with the highest expression in
the approximately trimodal distribution seen in peripheral blood. For the remaining antigens, a threshold level was chosen that was able to exclude more
than 90% of cells when stained with nonspecific
antibody. To correct for background binding, each
value obtained from staining with specific antibody
was subtracted with values from staining with nonspecific antibody.
Results
To establish the phenotype of T lymphocytes in
human atherosclerotic plaques, cells were isolated
from carotid endarterectomy specimens by digestion
with collagenase, stained with MAbs to cell-surface
markers, and analyzed byflowcytometry. T lymphocytes were identified with a phycoerythrin-labeled
Leu-4 antibody directed to CD3, a membrane protein complex that is associated with the T-cell antigen
receptor and that is expressed on all T cells. The
same cells were then labeled with a panel of FITCtagged MAbs directed to different lymphocyte surface antigens. This permitted a detailed characterization of the T-cell population. For comparison, T cells
from the peripheral blood of patients were analyzed
in an identical way.
Tests with collagenase treatment of phytohemagglutinin-activated peripheral blood mononuclear
cells showed a negligible or no effect on reactivity of
any of the antibodies used except for anti-CD4
(Leu-3a), for which the reactivity was substantially
decreased. Residual CD4 reactivity, however, always
allowed delineation of CD4+ T cells. The difference
in phenotypes of plaque T cells and peripheral blood
T cells and the fact that virtually no B cells were
encountered among plaque lymphocytes (as assessed
by MAb Leu-12 towards CD19, not affected by
collagenase) indicate that contamination of peripheral blood cells in the plaque cell population was very
low or absent. The representativity of the plaque
T-cell samples obtained after collagenase digestion
was supported by the correspondence of T-cell phenotypes with findings in previous immunohistochemical studies.1*5 In all patients, the majority of plaque T
cells carried the common a/J-type antigen receptor.
In two patients, the amounts of T cells expressing the
-yS-type antigen receptor were 6% and 8%, respectively, which were slightly higher than those in peripheral blood (data not shown). Fifty-five percent of
the plaque lymphocytes were CD8+ cytotoxic T cells,
and the remainder were of the CD4+ helper pheno-
208
Arteriosclerosis and Thrombosis
Vol 12, No 2 February 1992
type. In peripheral blood, 46% of T cells were CD8+,
but this difference was not statistically significant.
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Memory Cell Phenotype of Plaque T Lymphocytes
Immunologically naive T cells differ from memory
cells in their expression of the CD45 antigen. The
CD45, or leukocyte common antigen (LCA), is a
family of all surface tyrosine phosphatases expressed
on all types of leukocytes. The protein is encoded by
a single gene, and the different forms are obtained
through alternative splicing of the large primary
transcript.9 Naive T lymphocytes never previously
activated express the 205-220-kd form CD45RA of
LCA, which is recognized by the MAb 2H4. However, after the first round of activation of the T cell
through exposure to its specific antigen, the splicing
of the primary transcript is altered so that the 180 -kd
form, CD45RO, which is recognized by the antibody
UCHL1, is expressed instead.1011 Reactivity to
UCHL1 can thus be used as a marker for previously
activated T lymphocytes.
CD45R0
10"
CD45RA
101
10"
10'
10"
10'
10"
10
10'
10-
10"
10"
10'
10*
10
»•
10"
Control
The numbers of CD45RO+ and CD45RA+ T cells
were inversely correlated in plaque cells as well as in
the peripheral blood of patients (Figure 1). The
pattern of CD45 isoform expression was, however,
distinctly different in the plaque compared with that
in blood. The mean proportion of CD45RO+ T cells
was 49% in peripheral blood but was increased to
64% among plaque T cells (Figure 2). A similar
discrepancy, even more pronounced, was seen in the
expression of CD45RA. Forty-four percent of T cells
in peripheral blood expressed CD45RA compared
with only 12% in plaque T cells (Figure 2).
These data indicate that the majority of plaque T
lymphocytes belong to the memory-T-cell subset. This
implies that they have previously undergone activation,
but it remains unclear whether the activation step
occurred before or after cell entry into the plaque.
Markers of Activation in Plaque T Lymphocytes
CD45RO is expressed on activated T cells as well
as on resting memory T cells. CD45RO expression,
therefore, gives no information about the degree of
activation at the time of analysis. To determine this,
a panel of five different antibodies recognizing surface antigens expressed at different time points after
T cell activation was used.
The high-affinity interleukin-2 receptor, the receptor for autocrine T-cell growth factor interleukin-2, is
not expressed on resting T cells but is induced within
24 hours after activation.12 The present study showed
that interleukin-2 receptor expression was low among
plaque T cells, and the frequency of positive cells did
not differ significantly from that in peripheral blood
(Figure 3). This suggests that the number of proliferating T cells is low in advanced human atherosclerotic plaques.
Other cell-surface proteins show slower kinetics of
expression after T-cell activation. In cell culture,
CD26 (Tal) expression is induced 2-5 days after
activation with phytohemagglutinin.13 HLA-DR and
CD45RA
CD45RO
o
o
<D
10'
10*
Plaque
10
10 u
1
"n
o
Peripheral
blood
CO
10'
10*
FIGURE 1. Representative histograms showing CD45RO
(upper panel) and CD45RA (middle panel) expression in T
cells from plaque (left) and peripheral blood (right). Cell
suspensions from plaque or peripheral blood mononuclear cell
preparations were double-labeled with phycoerythrin-conjugated anti-CD3 and FITC-labeled UCHL1 (CD45RO), 2H4
(CD45RA), or control mouse immunoglobulin G antibody
and analyzed by flow cytometry. CD3-positive cells were gated
and plotted in histograms, with cell numbers on they axis and
the logarithm of FITC fluorescence intensity on the x axis.
FFTC, fluorescein isothiocyanate.
Q.
Q
O
Plaque
Peripheral
blood
FIGURE 2. Bar graph showing distribution ofCD45RO+ and
CD45RA+ T cells in plaque and peripheral blood. T cells were
identified with phycoerythrin-conjugated anti-CD3 and were
double-labeled with FITC-tagged antibodies. A threshold level
for positive cells was determined for each antigen and then
applied on all samples. Error bars represent SEM, n=7J.
FITC, fluorescein isothiocyanate.
Stemme et al
Flow Cytometric Analysis of Plaque T Cells
•On
J2
Peripheral blood
8
Plaque
209
itS^T
VLA-1
10°
IL-2R
CD38
HLA-DR
CD26
VLA-1
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FIGURE 3. Bar graph of cells positive for a panel of activation markers in T cells from plaque and peripheral blood.
Experimental conditions were as described in the legend to
Figure 2. Error bars represent SEM, n=12. Differences between mean values of blood and plaque T cells are significant
for HLA-DR, CD26, and very late activation antigen-1
(VLA-1) (p<0.001, Mann-Whitney U test). IL-2R, interleukxn-2 receptor.
CD38 (OKT10) show a similar pattern of expression,
starting 5-6 days after antigen stimulation.14 These
surface markers are gradually downregulated approximately 1 week after cessation of stimulation in
vitro. They can thus be considered markers of relatively recent activation.
In the present study, the proportion of CD26+ T
cells was doubled in plaque cells compared with that
in peripheral blood, and the proportion of HLA-DR+
T cells was also significantly increased (Figure 3).
The expression of these surface antigens indicates
that the proportion of recently activated T cells is
increased in the plaque compared with that in the
peripheral blood.
In contrast to the antigens discussed above, VLA-1
is expressed 2-3 weeks after stimulation with mitogen and remains on the cell surface for a longer
time.1516 In the present study, more than 31% of
plaque T cells were VLA-1+ (Figures 3 and 4),
whereas only 1% of T cells in peripheral blood
expressed VLA-1. The surface phenotype of T lymphocytes from peripheral blood of the patients did
not differ significantly from that of T lymphocytes
from healthy blood donors (data not shown).
Discussion
The present study demonstrates that the T-cell
populations in advanced atherosclerotic plaques are
distinctly different from those in peripheral blood
from the same individuals. Forty-four percent of the
T cells in blood expressed the high-molecular-weight
(CD45RA) form of LCA that is characteristic for
naive T cells. In contrast, only 12% of plaque T cells
were of the naive phenotype. Similarly, 64% of
plaque T cells exhibited the memory (CD45RO)
phenotype compared with 49% in the blood. The
selective accumulation of memory-type T cells argues
strongly against entrapment of inactive circulating
cells as a significant mechanism for recruitment of T
101
102
101
102
10
10°
10
,o
io°"7o'""io21 -ios
Control so
. o 7 o 7 o
Plaque
Peripheral
blood
FIGURE 4. Representative histograms showing very late activation antigen-1 (VLA-1) expression in T cells from plaque
and peripheral blood. Experimental conditions were as described in the legend to Figure 1.
cells in advanced atherosclerotic lesions. Instead,
they suggest that T cells are activated locally in the
plaque, or alternatively, that circulating activated or
memory T cells may be selectively recruited to the
plaque. The dominance of memory T cells in the
plaque per se does not indicate that local activation
occurs. The expression of other phenotypic markers
suggests, however, that many of these T cells are
activated or maintained in an activated state in the
plaque.
The differential expression of activation markers
with different kinetics revealed an interesting aspect
of the T-cell activation state in the plaque. The
interleukin-2 receptor, which is rapidly induced after
activation but is then quickly downregulated, was not
increased in plaque T cells. HLA-DR and CD26,
which can be considered as activation markers with
intermediate-kinetic characteristics, were increased
approximately twofold. In contrast, the CD38 antigen
was not significantly increased in plaque T cells.
After in vitro activation, the expression of CD38
paralleled the expression of HLA-DR.14 This discrepancy may indicate that the surface expression
pattern of this antigen in vivo differs from that in
vitro. Finally, VLA-1 was increased more than 10fold in plaque tissue compared with that in the
patients' blood. Taken together, this pattern suggests
that a large proportion of plaque T cells are in a state
of late or chronic activation. These phenotypic characteristics resemble those observed for T cells in
other chronic inflammatory diseases, including rheumatoid arthritis,17-20 multiple sclerosis,21 sarcoidosis,22 and Graves' disease23 and may reflect common
mechanisms in the development of the inflammatory
infiltrates in these disorders.
The expression of VLA-1 is interesting not only as
a marker of activation but also because it may be of
210
Arteriosclerosis and Thrombosis Vol 12, No 2 February 1992
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functional significance for T-cell interactions with the
extracellular matrix in vascular tissue. VLA-1 is a
member of the /Jl subfamily of the large integrin
family of cell adhesion molecules.16-24 VLA-1 serves
as a cellular receptor for collagen and laminin16 and
thus anchors the cell to the extracellular matrix. It
has, therefore, been proposed that upregulation of
VLA-1 and other integrin receptors is important for
extravasation and local accumulation of lymphocytes
during the inflammatory response.16
In addition, matrix molecules may regulate lymphokine secretion through their interaction with integrin receptors.25 It has, for example, been shown
that collagen and laminin can enhance the activation
of T cells, while tenascin suppresses their activation.26 The expression of VLA-1 and other integrins
in the late phase of T-cell activation may therefore be
a mandatory requirement for adhesion to matrix
molecules and local tissue accumulation and serve as
a basis for local modulation of the inflammatory
response via matrix-integrin interactions. Collagens
and laminin are abundant in plaque tissue27 and
would be expected to retain VLA-1+ T cells in the
local environment and possibly also enhance thenstate of activation. In contrast, the matrix protein
tenascin, which is present in substantial concentrations in the arterial intima after experimental injury,
may inhibit the local immune response.27
T cells have been shown to control important functions of vascular cells by secreting lymphokines that
regulate gene expression in endothelial and smooth
muscle cells.28 For instance, endothelial cells respond
to interferon--y by expressing histocompatibility proteins, and in this way, they acquire the capacity to
present foreign antigens to the immune system.29 The
same cells respond to tumor necrosis factor and
interferon--y by expressing leukocyte adhesion molecules such as VCAM-1, ICAM-1, and ELAM-130-32
and by changing their growth pattern in endothelial
monolayers. Vascular smooth muscle cells are arrested in the Gt phase of the cell cycle by interferon•y,33 which inhibits growth, upregulates histocompatibility proteins,7 and inhibits expression of the
contractile protein a-actin.34
Several studies have demonstrated that the capacity to produce lymphokines is linked to the phenotype
of T lymphocytes. Naive T cells characterized by the
CD45RA+RO~ phenotype are deficient in interferon-y production,35 and such cells appear to be incapable of producing any lymphokine other than interleukin-2 during activation.8 This is functionally
reflected in their inability to help antibody-producing
cells.36
In contrast, in vitro activation of memory T cells
rapidly leads to transcription of the genes for interferon-% interleukins 3-6, and granulocyte/macrophage
colony stimulating factor and secretion of these lymphokines into the culture medium.8 Our finding that
CD45RA"RO+ memory T cells in a state of late
activation dominate the plaque therefore supports the
hypothesis that several lymphokines, including interfer-
on--y, granulocyte/macrophage colony stimulating factor, and interleukins 2-6, may be released locally in the
arterial wall during atherosclerosis.
In summary, the present study confirms and extends previous immunohistochemical observations
that the atherosclerotic plaque contains activated T
lymphocytes.3-5-37 An important new observation is
that the majority of plaque T cells are of the memory
phenotype. T cells of this differentiation stage have a
high capacity for lymphokine production, and many
plaque T cells exhibited phenotypic signs of late
activation, which further supports the hypothesis that
they are releasing lymphokines in the plaque. Finally,
the expression of integrin receptors by these cells
suggests that matrix interactions may be important
for the regulation of the local inflammatory response
in atherosclerosis.
Acknowledgment
We thank Beata Faber for excellent technical
assistance.
References
1. Jonasson L, Holm J, Skalli O, Bondjers G, Hansson GK:
Regional accumulations of T cells, macrophages, and smooth
muscle cells in the human atherosclerotic plaque. Arteriosclerosis 1986;6:131-138
2. Munro JM, VanDerWalt JD, Munro CS, Cox EL: An immunohistochemical analysis of human aortic fatty streaks. Hum
Pathol 1987;18:375-380
3. van der Wai AC, Das PK, Bentz van de Berg D, van der Loos
CM, Becker AE: Atherosclerotic lesions in humans: In situ
phenotypic analysis suggesting an immune mediated response.
Lab Invest 1989;61:166-170
4. Emeson EE, Robertson AL: T lymphocytes in aortic and
coronary intimas: Their potential role in atherogenesis. Am J
Pathol 1988;130:369-376
5. Hansson GK, Holm J, Jonasson L: Detection of activated T
lymphocytes in the human atherosclerotic plaque. Am J Pathol
1989;135:169-175
6. Jonasson L, Holm J, Skalli O, Gabbiani G, Hansson GK:
Expression of class II transplantation antigen on vascular
smooth muscle cells in human atherosclerosis. / Clin Invest
1985;76:125-131
7. Stemme S, Fager G, Hansson GK: MHC class II antigen
expression in human vascular smooth muscle cells is induced
by interferon-gamma and modulated by tumor necrosis factor
and lymphotoxin. Immunology 1990;69:243-249
8. Ehlers S, Smith KA: Differentiation of T cell lymphokine gene
expression: The in vitro acquisition of T cell memory. / Exp
Med 1991;173:25-36
9. Thomas ML: The leukocyte common antigen family. Annu Rev
Immunol 1989;7:339-369
10. Sanders ME, Makgoba MW, Shaw S: Human naive and
memory T cells: Reinterpretation of helper-inducer and suppressor-inducer subsets. Immunol Today 1988;9:195-199
11. Cerottini J-C, MacDonald HR: The cellular basis of T cell
memory. Annu Rev Immunol 1989;7:77-89
12. Waldmann TA: The structure, function, and expression of
interleukin-2 receptors in normal and malignant lymphocytes.
Science 1986^232:727-732
13. Fox DA, Hussey RE, Fitzgerald KA, Acuto O, Poole C, Palley
L, Daley JF, Schlossman SF, Reinhorz EL: Tal, a novel 105
kD human T cell activation antigen defined by a monoclonal
antibody. / Immunol 1984;133:1250-1256
14. Hercend T, Ritz J, Schlossman SF, Reinherz EL: Comparative
expression of T9, T10, and la antigens on activated human T
cell subsets. Hum Immunol 1981;3:247-259
Stemme et al
Downloaded from http://atvb.ahajournals.org/ by guest on May 5, 2017
15. Hemler ME, Jacobson JG, Brenner MB, Mann D, Strominger
JL: VLA-1: A T cell surface activation antigen which defines a
novel late stage of human T cell activation. Eur J Immunol
1985;15:5O2-5O8
16. Hemler ME: VLA proteins in the integrin family: Structures,
functions, and their role on leukocytes. Annu Rev Immunol
1990;8:365-400
17. Fox RI, Fong S, Sabharwal N, Carstens SA, Kung PC,
Vaughan JH: Synovialfluidlymphocytes differ from peripheral
blood lymphocytes in patients with rheumatoid arthritis.
J Immunol 1982;128:351-354
18. Hovdenes J, Gaudernack G, Kvien TK, Egeland T: Expression
of activation markers on CD4+ and CD8+ cells from synovial
fluid, synovial tissue and peripheral blood of patients with
inflammatory arthritides. Scand J Immunol 1989;29:631-639
19. Cush JJ, Lipsky PE: Phenotypic analysis of synovial tissue and
peripheral blood lymphocytes isolated from patients with
rheumatoid arthritis. Arthritis Rheum 1988;31:123O-1238
20. Hemler ME, Glass D, Coblyn JS, Jacobson JG: Very late
activation antigens on rheumatoid synovial fluid T lymphocytes. / Clin Invest 1986;78:696-702
21. Hafler DA, Fox DA, Manning ME, Schlossman SF, Reinherz
EL, Weiner HL: In vivo activated T lymphocytes in the
peripheral blood and cerebrospinal fluid of patients with
multiple sclerosis. N Engl J Med 1985;312:1405-1411
22. Saltini C, Hemler ME, Crystal RG: T lymphocytes compartmentalized on the epithelial surface of the lower respiratory
tract express the very late activation antigen complex VLA-1.
Arthritis Rheum 1988;46:221-233
23. Eguchi K, Ueki Y, Shimomura C, Otsubo T, Nakao H, Migita
K, Kawakami A, Matsunaga M, Tezuka H, Ishikawa N, Ito K,
Nagataki I: Increment in the Tal + cells in the peripheral blood
and thyroid tissue of patients with Graves' disease. / Immunol
1989;142:4233-4240
24. Albelda SM, Buck CA: Integrins and other cell adhesion
molecules. FASEB J 1990;4:2868-2880
25. Ofosu-Appiah W, Warrington RJ, Morgan K, Wilkins JA:
Lymphocyte extracellular matrix interactions: Induction of
interferon by connective tissue components. Scand J Immunol
1989;29:517-525
26. Ruegg CR, Chiquet-Ehrismann R, Alkan SS: Tenascin, an
extracellular matrix protein, exerts immunomodulatory activities. Proc NatlAcad Sci U S A 1989;86:7437-7441
Flow Cytometric Analysis of Plaque T Cells
211
27. Hedin U, Holm J, Hansson GK: Induction of tenascin in rat
arterial injury. Am J Pathol 1991,139:649-656
28. Hansson GK, Jonasson L, Seifert PS, Stemme S: Immune
mechanisms in atherosclerosis. Arteriosclerosis 1989;9:567-578
29. Geppert TD, Lipsky PE: Antigen presentation by interferongamma-treated endothelial cells and fibroblasts: Differential
ability to function as antigen-presenting cells despite comparable la expression. / Immunol 1985;135:3750-3762
30. Osborn L, Hession C, Tizard R, Vassallo C, Lukowskyj S,
Chi-Rosso G, Lobb R: Direct expression cloning of vascular
cell adhesion molecule 1, a cytokine-induced endothelial
protein that binds to lymphocytes. Cell 1989^9:1203-1211
31. Rothlein R, Dustin ML, Marlin SD, Springer TA: A human
intercellular adhesion molecule (ICAM-1) distinct from
LFA-1. / Immunol 1986;137:1270-1274
32. Bevilacqua MP, Stengalin S, Gimbrone MA, Seed B: Endothelial leukocyte adhesion molecule-1: An inducible receptor
for neutrophils related to complement regulatory proteins and
lectins. Science 1989;243:1160-1165
33. Hansson GK, Jonasson L, Holm J, Clowes MM, Clowes AW:
Gamma-interferon regulates vascular smooth muscle proliferation and la antigen expression in vivo and in vitro. Ore Res
1988;63:712-719
34. Hansson GK, Hellstrand M, Rymo L, Rubbia L, Gabbiani G:
Interferon-gamma inhibits both proliferation and expression
of differentiation-specific alpha-smooth muscle actin in arterial smooth muscle cells. / Exp Med 1989;170:1595-16O8
35. Sanders ME, Makgoba MW, Shanow SO, Stepkany D,
Springer TA, Young HA, Shaw S: Human memory T lymphocytes express increased levels of three cell adhesion molecules
(LFA-3, CD2, and LFA-1) and three other molecules
(UCHL1, CDw29, and Pgp-1) and have enhanced IFN-gamma
production. / Immunol 1988;140:1401-1407
36. Tedder TF, Clement LT, Cooper MD: Human lymphocyte
differentiation antigens HB-10 and HB-11: II. Differential
production of B cell growth and differentiation factors by
distinct helper T cell subpopulations. J Immunol 1985;134:
2989-2994
37. Hansson GK, Jonasson L, Lojsthed B, Stemme S, Kocher O,
Gabbiani G: Localization of T lymphocytes and macrophages
in fibrous and complicated human atherosclerotic plaques.
Atherosclerosis 1988;72:135-141
KEYWORDS • atherosclerosis • Tlymphocytes • flowcytometry
• activation
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T lymphocytes in human atherosclerotic plaques are memory cells expressing CD45RO and
the integrin VLA-1.
S Stemme, J Holm and G K Hansson
Arterioscler Thromb Vasc Biol. 1992;12:206-211
doi: 10.1161/01.ATV.12.2.206
Arteriosclerosis, Thrombosis, and Vascular Biology is published by the American Heart Association, 7272 Greenville
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Copyright © 1992 American Heart Association, Inc. All rights reserved.
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