The Journal of Immunology, 1999, 163: 1128-1131.
Copyright © 1999 by The American Association of Immunologists
Cutting Edge: Lymphoproliferative Disease in the Absence of CTLA-4 Is Not T Cell Autonomous1
Martin F. Bachmann2,*,
Gabriele Köhler
,
Barbara Ecabert*,
Tak W. Mak
and
Manfred Kopf*
*
Basel Institute for Immunology, Basel, Switzerland;
Department of Pathology, University of Freiburg, Freiburg, Germany; and
Amgen Institute, Toronto, Ontario, Canada
 |
Abstract
|
|---|
Mice deficient for the expression of CTLA-4 develop a lethal
lymphoproliferative syndrome and multiorgan inflammation leading to
death at about 4 wk of age. Here we show that RAG2-deficient mice
reconstituted with CTLA-4-deficient bone marrow do not develop a
lymphoproliferative syndrome despite lymphocyte infiltration mainly
into pericardium and liver. Moreover, RAG2-deficient mice reconstituted
with a mixture of normal and CTLA-4-deficient bone marrow remain
healthy and do not develop any disease. Thus, the lethal disease
observed in CTLA-4-deficient mice is not T cell autonomous and can be
prevented by factors produced by normal T cells.
 |
Introduction
|
|---|
T
cell activation is a complex process that is tightly regulated by TCR
and costimulatory signals. Stimulation of T cells through the TCR alone
is usually inefficient and/or results in clonal anergy. In contrast,
concomitant triggering of the TCR and CD28, the major costimulatory
molecule on T cells, leads to full activation of T cells and the
generation of T cell memory (1, 2). The role of CTLA-4, a
homologue of CD28 also binding to B7-1 and B7-2, is less well defined.
Initially, it was characterized as a costimulatory molecule
(3), but subsequent experiments established that it was
more likely delivering an inhibitory signal (4, 5, 6).
Despite some evidence that CTLA-4 may be dispensable for
down-regulation of primary anti-viral T cell responses (7, 8) or may even act as a costimulatory molecule (9, 10), it is now generally believed that CTLA-4 turns T cells off.
Biochemical studies suggesting that CTLA-4 recruits phosphatases to the
TCR complex leading to its inactivation support this view (11, 12). The most impressive argument that CTLA-4 functions as a
negative regulator of T cells is made by CTLA-4-deficient
(CTLA-4-/-) mice that die within 4 wk after
birth due to a lymphoproliferative disorder and multiorgan inflammation
(13, 14, 15). Thus, CTLA-4 expression by activated T cells
seems to be required for turning these T cells off to prevent
uncontrolled lymphoproliferation. Our current study indicates that this
view has to be reconciled because bone marrow chimeras harboring
CTL-4-/- T cells may develop infiltration of
pericardium and liver but do not develop a lymphoproliferative
syndrome. Moreover, mixed bone marrow chimeras producing
CTLA-4-/- and normal T cells are healthy and do
not develop disease, demonstrating that the lymphoproliferative
disorder observed in CTLA-4-/- mice is not due
to a T cell autonomous defect.
 |
Materials and Methods
|
|---|
Mice and generation of bone marrow chimeras
CTLA-4-/- (13) and
RAG2-/- (16) mice have been
described previously. CTLA-4-deficient mice were bred heterozygously,
and offspring were genotyped by PCR at the age of 23 wk and
immediately used to generate bone marrow chimeras. A total of
107 cells depleted of mature
CD4+ and CD8+ T cells (by
negative selection using monoclonal anti-CD4 and anti-CD8 Abs
and magnetic beads (Dynal) according to the manufacturers
instructions) were transferred per RAG2-/-
recipient (irradiated with 3 Gy). Mixed bone marrow chimeras were
reconstituted with an equal number of bone marrow cells derived from
CD45.2 CTLA4-/- mice and CD45.1 congenic
C57BL/6 mice. Similar results were obtained if a total of
107 cells or 107 cells of
each genotype were transferred to generate the mixed chimeras. No
differences could be observed between mice reconstituted with
CTLA-4+/+ and CTLA-4+/-
bone marrow. For simplicity, such bone marrow is therefore referred to
as CTLA-4+/+.
Analysis of T cell activation markers
Lymph node cells from the bone marrow chimeras were harvested
and triple stained for the expression of CD4 (FITC)/CD8 (PE) and CD25
(biotin), CD44 (biotin), CD62L (biotin), or CD69 (biotin) followed by
streptavidin coupled to APC. Lymph node cells from mixed bone marrow
chimeras were triple stained for the expression of CD45.2 (biotin)
followed by streptavidin coupled to APC, CD4 (FITC), and CD8 (PE) or
CD45.2 (FITC), CD4 (PE) or CD8 (PE), and CD25 (biotin), CD44 (biotin),
CD62L (biotin), or CD69 (biotin) followed by streptavidin coupled
to APC.
Histology
Organs were isolated from chimeric mice 8 wk after
reconstitution at a time point when the mice that obtained
CTLA-4-/- bone marrow alone had developed signs
of disease. Organs were fixed in 4% buffered formaldehyde in PBS, pH
7.0, and were paraffin embedded. Sections were cut (5 µM) and stained
with hematoxylin and eosin and examined by light microscopy.
Quantitative RT-PCR
Total cellular RNA was prepared from CD45.1
(CTLA-4+/+) and CD45.2
(CTLA-4-/-) splenocytes purified from mixed
chimeras 8 wk after bone marrow transfer. Random hexamer-primed reverse
transcription was performed and the level of TGF-
-, IFN-
-, and
IL-10-specific transcripts was determined by PCR coamplification of a
competitor construct and cellular cDNA after standardization for the
expression of
2-microglobulin essentially as
described (17). PCR primers for TGF-
, IFN-
, IL-10,
and
2-microglobulin were described elsewhere
(17).
 |
Results and Discussion
|
|---|
To analyze whether the lymphoproliferative disorder observed in
CTLA-4-/- mice was T cell autonomous or could
be prevented by the presence of normal T cells, various bone marrow
chimeras were constructed. Thus, irradiated (3 Gy)
RAG2-/- mice were reconstituted with T
cell-depleted bone marrow from normal mice,
CTLA-4-/- mice, or a 1:1 mixture of both. In
case of the latter, we reconstituted CTLA-4-/-
bone marrow expressing CD45.2 together with bone marrow of congenic
C57BL/6 mice expressing CD45.1 on all hematopoietic cells so that we
could follow the fate of the individual T cell populations. While
CTLA-4-/- mice die shortly (35 wk) after
birth (13, 14, 15), RAG2-/- chimeras
receiving CTLA-4-deficient bone marrow alone died around week 10 after
reconstitution. In marked contrast, the mixed bone marrow chimeras
remained healthy for at least 6 mo (Fig. 1
A). Mixed chimerism was
confirmed by assessing CD45.2 expression of CD4+
and CD8+ T cells (Fig. 1
B). Similar
results were obtained between 8 and 40 wk after reconstitution and was
comparable in the T and B cell compartment (not shown). Histological
analysis of organs derived from diseased
CTLA-4-/- chimeras revealed inflammatory
lymphocyte infiltrates mainly in pericardium with slight myocardial
involvement (Fig. 2
C) and
liver (not shown). However, inflammation was clearly less extensive
than in 4-wk-old CTLA-4-/- mice (Fig. 2
D) and was not present in all
CTLA-4-/- chimeras (not shown). In contrast,
mixed bone marrow chimeras as well as control chimeras showed no signs
of organ inflammation (Fig. 2
, A and B). Thus,
chimeras receiving CTLA-4-/- bone marrow alone
developed lethal inflammation of multiple organs. However, this disease
could be prevented by the presence of normal T cells, demonstrating
that disease does not develop because T cells stimulated through the
TCR have to be down-regulated by a signal mediated by CTLA-4. Instead,
normal T cells appear to produce a factor (or factors) upon ligation of
CTLA-4 that is able to prevent organ inflammation in trans.
Interestingly, assessing lymphocyte numbers in spleen and lymph nodes
in the various chimeras revealed normal cell numbers, indicating that
CTLA-4-/- T cells fail to cause
lymphoproliferative disease even in the absence of normal T cells (Fig. 3
A). Moreover, the
architecture of the lymph nodes was normal in all types of chimeric
mice, while it was grossly distorted in
CTLA-4-/- mice (not shown).

View larger version (76K):
[in this window]
[in a new window]
|
FIGURE 2. Mixed bone marrow chimeras do not develop multifocal organ
infiltration. RAG-2-deficient mice were reconstituted with T
cell-depleted bone marrow derived from control mice alone
(A), from both control plus CTLA-4-deficient mice
(B), or from CTLA-4 deficient mice alone
(C) and the heart was examined by histology. For
comparison, the heart of a 4-wk-old CTLA-4-deficient mouse was included
(D). Bar represents 100 µm.
|
|

View larger version (33K):
[in this window]
[in a new window]
|
FIGURE 3. CTLA-4-deficient T cells fail to induce lymphoproliferative disease in
chimeric mice. RAG2-deficient mice were reconstituted with T
cell-depleted bone marrow derived from control (CD45.1) or
CTLA-4-deficient (CD45.2) mice or a mixture of the two.
A, Lymphocyte numbers in spleens and pooled mesenteric
lymph nodes were assessed 8 wk later. B, Expression of
IL-2R -chain and forward scatter (FSC) is shown for CD4+
T cells derived from the various chimeras. a,
RAG2-/- mice receiving control bone marrow.
b, RAG2-/- mice receiving
CTLA-4-/- bone marrow. c and
d, RAG2-/- mice receiving control (CD45.1)
and CTLA-4-deficient (CD45.2) bone marrow. Cells were triple stained
for the expression of CD45.1/CD45.2, IL-2R -chain, and CD4. The
percent IL-2R-positive cells and average FSC are indicated in the
figures. One representative experiment of three is shown.
C, Spleen cells were isolated from mixed chimeras and
sorted for the expression of CD45.2 and CD45.1. After standardization
for expression of 2-microglobulin, the presence of
TGF- mRNA was assessed by quantitative RT-PCR at 0, 1, and 2 days
after in vitro stimulation with anti-CD3 Abs. The upper band
represent the competitor (19,500 molecules).
|
|
CD4+ T cells are the first cells to become
activated in CTLA-4-/- mice (15).
In contrast, analysis of various activation markers expressed by the
CD4+ T cells derived from the mixed chimeras did
not reveal any uncontrolled activation of CTLA-4-deficient T cells.
Specifically, both CD45.1+ (control) and
CD45.2+ (CTLA-/-)
CD4+ T cells exhibited comparable expression of
the IL-2R
-chain and forward scatters as measures for activation
(Fig. 3
B). Interestingly, CD4+ T cells
in chimeras that received bone marrow from
CTLA-4-/- mice alone exhibited up-regulated
expression of IL-2R
and were blasted, indicating that they were
activated (Fig. 3
B). Similar observations were made for
CD8+ T cells and for the expression of CD69,
CD44, and CD62L (not shown). T cells derived from
CTLA-4-/- mice that develop lymphoproliferative
disorder show hyperphosphorylation (11).
By contrast, T cells isolated from the chimeras were not
hyperphosphorylated, again indicating that these
CTLA-4-/- T cells are not activated in such an
uncontrolled manner, as observed in the knockouts (not shown).
Thus, our results demonstrate that T cells devoid of CTLA-4 expression
do not develop lymphoproliferative disorder, but may cause multiorgan
inflammation. However, this disease, can be prevented by a factor (or
factors) produced by normal T cells. The recent finding that CTLA-4
triggers the production TGF-
(18) together with the
observation that TGF-
-/- mice develop
multifocal inflammation in various organs (19, 20) may
suggest that the principle reason for disease in
CTLA-4-/- mice is a failure to produce TGF-
or related factors rather than defective down-regulation of T cell
activation in CTLA-4-deficient T cells. However,
CTLA-4-/- T cells isolated from mixed chimeras
expressed normal levels of TGF-
(Fig. 3
C), IL-10, and
IFN-
(not shown) mRNA upon freshly after isolation and after
stimulation with anti-CD3. Although this result demonstrates that
CTLA-4-/- T cells can produce antiinflammatory
cytokines such as TGF-
and IL-10, it remains possible that the
CTLA-4-/- T cells have been instructed in vivo
by normal TGF-
- and IL-10-producing T cells to themselves be
committed to the generation of these cytokines. This interpretation is
compatible with the recent observation that exogenous TGF-
and IL-10
can trigger their own production in Th cells, in this way replacing the
CTLA-4 signal. (21, 22).
Our data demonstrate that the disease observed in
CTLA-4-/- mice is not due to a T cell
autonomous defect. By contrast, CTLA-4 triggering on normal T cells
stimulates the production of a factor (or factors) that are sufficient
to inhibit disease induced by CTLA-4-/- T
cells. Thus, our results suggest that the CTLA-4-recruited phosphatases
that dephosphorylate molecules of the CD3 complex
(11, 12) may not lead to complete inactivation of T cells
but may reduce TCR-mediated signals to the extent that the cytokine
production is shifted to the production of TGF-
. The here-described
healthy chimeras containing both normal and CTLA-4-deficient T cells
will allow us to definitively assess the in vivo role of CTLA-4 in
regulating specific T cell responses.
 |
Acknowledgments
|
|---|
We thank Karin Lefrang for excellent technical assistance and
H. Rodewald, E. Palmer, and A. Viola for critically
reading the manuscript and for helpful discussions.
 |
Footnotes
|
|---|
1 The Basel Institute for Immunology is founded and supported by F. Hoffmann-La Roche, Basel, Switzerland. 
2 Address correspondence and reprint requests to Dr. Martin F. Bachmann, Basel Institute for Immunology, Grenzacherstrasse 487, 4005 Basel, Switzerland. E-mail address: 
Received for publication April 27, 1999.
Accepted for publication June 3, 1999.
 |
References
|
|---|
-
Linsley, P. S., J. A. Ledbetter. 1993. The role of the CD28 receptor during T cell responses to antigen. Annu. Rev. Immunol. 11:191.[Medline]
-
Lenschow, D. J., T. L. Walunas, J. Bluestone. 1996. CD28/B7 system of T cell costimulation. Annu. Rev. Immunol. 14:259.[Medline]
-
Linsley, P. S., J. L. Greene, J. Tan, T. J. Bradshaw, J. A. Ledbetter, C. Anasetti, N. K. Damle. 1992. Coexpression and functional cooperation of CTLA-4 and CD28 on activated T lymphocytes. J. Exp. Med. 176:1595.[Abstract/Free Full Text]
-
Walunas, T. L., D. J. Lenschov, C. Y. Bakker, P. S. Linsley, G. J. Freeman, J. M. Greene, C. B. Thompson, J. A. Bluestone. 1994. CTLA-4 can function as a negative regulator of T cell activation. Immunity 1:405.[Medline]
-
Krummel, M. F., J. P. Allison. 1995. CD28 and CTLA-4 have opposing effects on the response of T cells to stimulation. J. Exp. Med. 182:459.[Abstract/Free Full Text]
-
Karandikar, N., C. L. Vanderlugt, T. L. Walunas, S. D. Miller, J. A. Bluestone. 1996. CTLA-4: a negative regulator of autoimmune diesease. J. Exp. Med. 184:783.[Abstract/Free Full Text]
-
Bachmann, M. F., P. Waterhaus, D. Speiser, K. McKall-Faienza, T. W. Mak, P. S. Ohashi. 1998. Normal responsiveness of CTLA-4-deficient anti-viral cytotoxic T cells. J. Immunol. 160:95.[Abstract/Free Full Text]
-
Chambers, C. A., T. J. Sullivan, T. Truong, J. P. Allison. 1998. Secondary but not primary T cell responses are enhanced in CTLA-4-deficient CD8+ T cells. Eur. J. Immunol. 28:3137.[Medline]
-
Wu, Y., Y. Guo, A. Huang, P. Zheng, Y. Liu. 1997. CTLA-4-B7 interaction is sufficient to costimulate T cell clonal expansion. J. Exp. Med. 185:1327.[Abstract/Free Full Text]
-
Zheng, P., Y. Wu, Y. Guo, C. Lee, Y. Liu. 1998. B7-CTLA4 interaction enhances both production of antitumor cytotoxic T lymphocytes and resistance to tumor challenge. Proc. Natl. Acad. Sci. USA 95:6284.[Abstract/Free Full Text]
-
Marengere, L. E. M., P. Waterhouse, G. Duncan, H.-W. Mittrücker, G.-S. Feng, T. W. Mak. 1996. Regulation of T cell receptor signaling by tyrosine phosphatase SYP association with CTLA-4. Science 272:1170.[Abstract]
-
Lee, K. M., E. Chuang, M. Griffin, R. Khattri, D. K. Hong, W. Zhang, D. Straus, L. E. Samelson, C. B. Thompson, J. A. Bluestone. 1998. Molecular basis of T cell inactivation by CTLA-4. Science 282:2263.[Abstract/Free Full Text]
-
Waterhouse, P., J. M. Penninger, E. Timms, A. Wakeham, A. Shahinian, K. P. Lee, C. B. Thompson, H. Griesser, T. W. Mak. 1995. Lymphoproliferative disorders with early lethality in mice deficient in CTLA-4. Science 270:985.[Abstract/Free Full Text]
-
Tivol, E. A., F. Borriello, A. N. Schweitzer, W. P. Lynch, J. A. Bluestone, A. H. Sharpe. 1995. Loss of CTLA-4 leads to massive lymphoproliferation and fatal multiorgan destruction, revealing a critical negative regulatory role of CTLA-4. Immunity 3:541.[Medline]
-
Chambers, C. A., T. J. Sullivan, J. P. Allison. 1997. Lymphoproliferation in CTLA-4-deficient mice is mediated by costimulation-dependent activation of CD4+ T cells. Immunity 7:885.[Medline]
-
Shinkai, Y., G. Rathbun, K. P. Lam, E. M. Oltz, V. Stewart, M. Mendelsohn, J. Charron, M. Datta, F. Young, A. M. Stall, F. W. Alt. 1992. RAG-2-deficient mice lack mature lymphocytes owing to inability to initiate V(D)J rearrangement. Cell 68:855.[Medline]
-
Kopf, M., F. Brombacher, G. Kohler, G. Kienzle, K. H. Widmann, K. Lefrang, C. Humborg, B. Ledermann, W. Solbach. 1996. IL-4-deficient BALB/c mice resist infection with Leishmania major. J. Exp. Med. 184:1127.[Abstract/Free Full Text]
-
Chen, W., W. Jin, S. M. Wahl. 1998. Engagement of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) induces transforming growth factor
(TGF-
) production by murine CD4(+) T cells. J. Exp. Med. 188:1849.[Abstract/Free Full Text]
-
Shull, M. M., I. Ormsby, A. B. Kier, S. Pawlowski, R. J. Diebold, M. Yin, R. Allen, C. Sidman, G. Proetzel, D. Calvin, et al 1992. Targeted disruption of the mouse transforming growth factor-
1 gene results in multifocal inflammatory disease. Nature 359:693.[Medline]
-
Kulkarni, A. B., C. G. Huh, D. Becker, A. Geiser, M. Lyght, K. C. Flanders, A. B. Roberts, M. B. Sporn, J. M. Ward, S. Karlsson. 1993. Transforming growth factor
1 null mutation in mice causes excessive inflammatory response and early death. Proc. Natl. Acad. Sci. USA 90:770.[Abstract/Free Full Text]
-
Seder, R. A., T. Marth, M. C. Sieve, W. Strober, J. J. Letterio, A. B. Roberts, B. Kelsall. 1998. Factors involved in the differentiation of TGF-
-producing cells from naive CD4+ T cells: IL-4 and IFN-
have opposing effects, while TGF-
positively regulates its own production. J. Immunol. 160:5719.[Abstract/Free Full Text]
-
Groux, H., A. OGarra, M. Bigler, M. Rouleau, S. Antonenko, J. E. de Vries, M. G. Roncarolo. 1997. A CD4+ T-cell subset inhibits antigen-specific T-cell responses and prevents colitis. Nature 389:737.[Medline]
This article has been cited by other articles:

|
 |

|
 |
 
Y. Zheng, C. N. Manzotti, F. Burke, L. Dussably, O. Qureshi, L. S. K. Walker, and D. M. Sansom
Acquisition of Suppressive Function by Activated Human CD4+CD25- T Cells Is Associated with the Expression of CTLA-4 Not FoxP3
J. Immunol.,
August 1, 2008;
181(3):
1683 - 1691.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
H.-P. Raue and M. K. Slifka
Pivotal Advance: CTLA-4+ T cells exhibit normal antiviral functions during acute viral infection
J. Leukoc. Biol.,
May 1, 2007;
81(5):
1165 - 1175.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
K. F. May Jr., X. Chang, H. Zhang, K. D. Lute, P. Zhou, E. Kocak, P. Zheng, and Y. Liu
B7-Deficient Autoreactive T Cells Are Highly Susceptible to Suppression by CD4+CD25+ Regulatory T Cells
J. Immunol.,
February 1, 2007;
178(3):
1542 - 1552.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
L. Gattinoni, A. Ranganathan, D. R. Surman, D. C. Palmer, P. A. Antony, M. R. Theoret, D. M. Heimann, S. A. Rosenberg, and N. P. Restifo
CTLA-4 dysregulation of self/tumor-reactive CD8+ T-cell function is CD4+ T-cell dependent
Blood,
December 1, 2006;
108(12):
3818 - 3823.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
S. Read, R. Greenwald, A. Izcue, N. Robinson, D. Mandelbrot, L. Francisco, A. H. Sharpe, and F. Powrie
Blockade of CTLA-4 on CD4+CD25+ Regulatory T Cells Abrogates Their Function In Vivo
J. Immunol.,
October 1, 2006;
177(7):
4376 - 4383.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
J. J. Engelhardt, T. J. Sullivan, and J. P. Allison
CTLA-4 Overexpression Inhibits T Cell Responses through a CD28-B7-Dependent Mechanism
J. Immunol.,
July 15, 2006;
177(2):
1052 - 1061.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
D. Homann, W. Dummer, T. Wolfe, E. Rodrigo, A. N. Theofilopoulos, M. B. A. Oldstone, and M. G. von Herrath
Lack of Intrinsic CTLA-4 Expression Has Minimal Effect on Regulation of Antiviral T-Cell Immunity
J. Virol.,
January 1, 2006;
80(1):
270 - 280.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
C. L. Thio, T. L. Mosbruger, R. A. Kaslow, C. L. Karp, S. A. Strathdee, D. Vlahov, S. J. O'Brien, J. Astemborski, and D. L. Thomas
Cytotoxic T-Lymphocyte Antigen 4 Gene and Recovery from Hepatitis B Virus Infection
J. Virol.,
October 15, 2004;
78(20):
11258 - 11262.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
S. Anjos, A. Nguyen, H. Ounissi-Benkalha, M.-C. Tessier, and C. Polychronakos
A Common Autoimmunity Predisposing Signal Peptide Variant of the Cytotoxic T-lymphocyte Antigen 4 Results in Inefficient Glycosylation of the Susceptibility Allele
J. Biol. Chem.,
November 22, 2002;
277(48):
46478 - 46486.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
E. A. Tivol and J. Gorski
Re-establishing Peripheral Tolerance in the Absence of CTLA-4: Complementation by Wild-Type T Cells Points to an Indirect Role for CTLA-4
J. Immunol.,
August 15, 2002;
169(4):
1852 - 1858.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
C. A. Chambers, J. Kang, Y. Wu, W. Held, D. H. Raulet, and J. P. Allison
The lymphoproliferative defect in CTLA-4-deficient mice is ameliorated by an inhibitory NK cell receptor
Blood,
May 29, 2002;
99(12):
4509 - 4516.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
J. L. LaBelle, C. A. Hanke, B. R. Blazar, and R. L. Truitt
Negative effect of CTLA-4 on induction of T-cell immunity in vivo to B7-1+, but not B7-2+, murine myelogenous leukemia
Blood,
March 15, 2002;
99(6):
2146 - 2153.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
F. Haspot, F. Villemain, G. Laflamme, F. Coulon, D. Olive, J. Tiollier, J.-P. Soulillou, and B. Vanhove
Differential effect of CD28 versus B7 blockade on direct pathway of allorecognition and self-restricted responses
Blood,
March 15, 2002;
99(6):
2228 - 2234.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
W. Dummer, B. Ernst, E. LeRoy, D.-S. Lee, and C. D. Surh
Autologous Regulation of Naive T Cell Homeostasis Within the T Cell Compartment
J. Immunol.,
February 15, 2001;
166(4):
2460 - 2468.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
T. J. Sullivan, J. J. Letterio, A. van Elsas, M. Mamura, J. van Amelsfort, S. Sharpe, B. Metzler, C. A. Chambers, and J. P. Allison
Lack of a role for transforming growth factor-beta in cytotoxic T lymphocyte antigen-4-mediated inhibition of T cell activation
PNAS,
February 15, 2001;
(2001)
51632398.
[Abstract]
[Full Text]
|
 |
|

|
 |

|
 |
 
S. da Rocha Dias and C. E. Rudd
CTLA-4 blockade of antigen-induced cell death
Blood,
February 15, 2001;
97(4):
1134 - 1137.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
A. Lanzavecchia and F. Sallusto
Dynamics of T Lymphocyte Responses: Intermediates, Effectors, and Memory Cells
Science,
October 6, 2000;
290(5489):
92 - 97.
[Abstract]
[Full Text]
|
 |
|

|
 |

|
 |
 
S. Read, V. Malmstrom, and F. Powrie
Cytotoxic T Lymphocyte-associated Antigen 4 Plays an Essential Role in the Function of CD25+CD4+ Regulatory Cells that Control Intestinal Inflammation
J. Exp. Med.,
July 17, 2000;
192(2):
295 - 302.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
T. Takahashi, T. Tagami, S. Yamazaki, T. Uede, J. Shimizu, N. Sakaguchi, T. W. Mak, and S. Sakaguchi
Immunologic Self-Tolerance Maintained by CD25+CD4+ Regulatory T Cells Constitutively Expressing Cytotoxic T Lymphocyte-associated Antigen 4
J. Exp. Med.,
July 17, 2000;
192(2):
303 - 310.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
E. L. Masteller, E. Chuang, A. C. Mullen, S. L. Reiner, and C. B. Thompson
Structural Analysis of CTLA-4 Function In Vivo
J. Immunol.,
May 15, 2000;
164(10):
5319 - 5327.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
T. J. Sullivan, J. J. Letterio, A. van Elsas, M. Mamura, J. van Amelsfort, S. Sharpe, B. Metzler, C. A. Chambers, and J. P. Allison
Lack of a role for transforming growth factor-beta in cytotoxic T lymphocyte antigen-4-mediated inhibition of T cell activation
PNAS,
February 27, 2001;
98(5):
2587 - 2592.
[Abstract]
[Full Text]
[PDF]
|
 |
|