| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
*
Immunology Research Division, Department of Pathology and
Renal Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
. In contrast to the effects on CD4+ Th
differentiation, the absence of CTLA-4 resulted in only a modest effect
on T cell proliferation, and increased proliferation of
CTLA-4-/- CD4+ T cells was seen only during
secondary stimulation in vitro. Administration of a stimulatory
anti-CD28 Ab in vivo induced IL-4 production in
CTLA-4-/- B7.1/B7.2-/- but not wild-type
mice. These studies demonstrate that CTLA-4 is a critical and potent
inhibitor of Th2 differentiation. Thus, the B7-CD28/CTLA-4 pathway
plays a critical role in regulating Th2 differentiation in two ways:
CD28 promotes Th2 differentiation while CTLA-4 limits Th2
differentiation. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The goal of the studies in this paper was to examine the role of CTLA-4 in T cell proliferation and differentiation. Much of our current knowledge of the function of CTLA-4 is based on experiments using agonistic and blocking Abs. Such studies have shown that CTLA-4 cross-linking inhibits cytokine secretion and cell cycle progression in T cells (8, 9). Many of these effects are the opposite of the demonstrated effects of CD28, which promotes early cytokine (e.g. IL-2) production, T cell survival by inducing expression of anti-apoptotic genes (e.g., Bcl-xL), and T cell differentiation into effector cells (10). CD28 plays an important role in differentiation of naive CD4+ T cells and influences Th2 differentiation more than Th1 development (11, 12). The role of CTLA-4 in Th cell differentiation is not yet clear.
Although the phenotype of the CTLA-4-/- mouse strain has been informative, the early activation of CTLA-4-/- T cells and death of these mice by 4 wk of age have limited the analyses that can be done using this strain. To overcome these problems, we have used two approaches to examine the obligatory roles of CTLA-4 in CD4+ T cell activation and differentiation. We have bred the DO11.10 class II-restricted TCR transgenic mice with CTLA-4-/- mice, and compared Ag-specific responses of wild-type and CTLA-4-/- CD4+ DO11.10 T cells. To exclude in vivo activation of CTLA-4-/- T cells by as yet unknown self or foreign Ags, we also have bred the CTLA-4-/- mice with mice lacking B7.1 and B7.2 (13, 14) and analyzed the responses of these CTLA-4-/- CD4+ T cells to anti-CD3 Ab plus wild-type APCs. Both approaches show that if CD4+ T cells are activated by TCR engagement and costimulation in the absence of CTLA-4, the cells exhibit a dramatic tendency to differentiate into Th2 populations. Surprisingly, the absence of CTLA-4 has only a modest effect on T cell proliferation, and only during secondary responses in vitro. These results suggest there is reciprocal regulation of CD4+ Th cell differentiation by CD28 and CTLA-4. CD28 promotes Th2 differentiation, whereas CTLA-4 is a critical, potent inhibitor of this differentiation pathway.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Mice expressing the DO11.10 TCR transgene, which responds to the peptide residues 323–339 of chicken OVA in the context of I-Ad (BALB/c), were obtained from Dr. Dennis Loh (Roche, Nutley, NJ) (15). CTLA-4 heterozygous (+/-) mice were backcrossed onto the BALB/c background for six generations before they were bred with the DO11.10 TCR transgenic mice and intercrossed. PCR typing for the DO11.10 transgene was conducted using primers of sequence 5'-CAG GAG GGA TCC AGT GCC AGC-3' and 5'-TGG CTC TAC AGT GAG TTT GGT-3'. Genotyping of CTLA-4 was done by Southern blot analysis or PCR analysis of tail DNA for the wild-type locus and the neomycin resistance gene in the targeted locus (5). In addition, a combination of primers was used to amplify neomycin and adjacent CTLA-4 sequence, using 5'-TTG CTC AAA GAA ACA GCA GAG-3' and 5'-GAC TAG GGG AGG AGT AGA AG-3'. CTLA-4-/- B7.1/B7.2-/- mice were generated by breeding 129S4Sv/Jae CTLA-4+/- mice with inbred 129S4/SvJae B7.1/B7.2-/- mice as described elsewhere (13). Mice were cared for according to institutional guidelines. Brigham and Women’s Hospital and Harvard Medical School are AAALAC (American Association for the Accreditation of Laboratory Animal Care) accredited institutions. Age-matched animals 6–18 wk old were used for experiments.
Reagents
HPLC-purified OVA peptide 323–339 (OVA323–339) with the sequence I-S-Q-A-V-H-A-A-H-A-E-I-N-E-A-G-R-COOH was obtained from Analytical Biotechnology Services (Boston, MA). The GK1.5 (anti-CD4), ADH4 (anti-CD8), 145-2C11 (anti-CD3), and PV-1 (anti-CD28) hybridomas were obtained from the American Type Culture Collection (Manassas, VA). Anti-Thy1.2 Ab was obtained from Serotec (Oxford, U.K.). Anti-CD4-FITC, anti-L-selectin-PE (CD62L), streptavidin-CyC, anti-IL4-PE, and PE-conjugated isotype control Abs were obtained from PharMingen (San Diego, CA). Purified, nonconjugated anti-IL-4 Ab, 11B11, was also obtained from PharMingen. The hybridoma for the KJ1-26 Ab, which recognizes the DO11.10 TCR transgene, was provided by Dr. P. Marrack (National Jewish Center, Denver, CO) (16) and affinity-purified Ab was biotinylated by standard methods.
Cell preparations
CD4+ T cells were obtained from pooled lymph nodes by positive magnetic selection using anti-CD4 (L3T4) Dynabeads and Detachabead (Dynal, Oslo, Norway) or magnetic columns (MACS) from Miltenyi Biotec (Auburn, CA). CD4+ cells were enriched for L-selectinhigh cells using MACS columns with anti-L-selectin beads from Miltenyi Biotec, or by staining cells with biotinylated KJ1-26 Ab and streptavidin-CyC, together with anti-CD4-FITC and anti-L-selectin-PE Abs and sterile cell sorting with a Coulter flow cytometer (Miami, FL). Comparable results were obtained with either method of cell isolation. Purities of populations were assessed by flow cytometry, with over 90% CD4+ purity and 80–90% purity of L-selectinhigh cells. APCs were prepared from splenocytes of BALB/c (for DO11.10) or 129/SvJae mice (for CTLA-4-/- B7.1/B7.2-/-) by treatment with anti-CD4 (GK1.5), anti-CD8 (ADH4), and anti-Thy1.2 Abs followed by rabbit Low-Tox complement (Accurate Chemical and Scientific, Westbury, NY). APCs were inactivated by treatment with 50 µg/ml Mitomycin C for 40 min at 37°C (Sigma, St. Louis, MO).
T cell cultures
For proliferation assays, purified T cells and APC were cultured with various concentrations of OVA peptide or anti-CD3 Ab in 200 µl of RPMI 1640 medium, as previously described (5). Supernatants for cytokine analysis, and T cells for restimulation assays, were harvested from 1 ml cultures initiated with 2 x 105 T cells, 2 x 106 APC, and OVA peptide concentrations as indicated. After 4 days, dead cells were removed with Lymphocyte Separation Medium (Organon Teknika, Durham, NC) and T cells were incubated overnight before restimulation with Ag and fresh APC. In some experiments, anti-IL-4 Ab (11B11) was added to the primary cultures at a concentration of 2 µg/ml.
Cytokine ELISA
Supernatants were analyzed for IL-2, IFN-, IL-4, IL-5, and
IL-10 by sandwich ELISA using Ab pairs and standards purchased from
PharMingen, according to the manufacturer’s instructions.
Intracellular cytokine staining
CD4+ T cells (5 x 105) were restimulated with 5 x 106 APC and OVA peptide for 3 days. Intracellular staining for IL-4 was performed as recommended by PharMingen. In brief, cells were activated with 10 ng/ml PMA and 1 µM ionophore for 4–6 h. Brefeldin A (10 µg/ml) was added during the last 2 h of the activation. Cells were fixed in 4% paraformaldehyde, then lysed in 0.5% saponin/1% BSA/0.1% NaN3 and incubated with a mixture of anti-CD4-FITC and anti-IL-4-PE or a PE-conjugated isotype control Ab.
In vivo administration of CD28
CTLA-4-/- B7.1/B7.2-/- or wild-type mice were injected i.v. with 100 µg of purified anti-CD28 Ab (PV-1) on days 0, 7, and 14 and sacrificed on day 19. Lymph node cells (2 x 105) were stimulated with various concentrations of anti-CD3 Ab (145-2C11), and cell cultures supernatants were harvested to measure cytokines at the indicated times.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Wild-type DO11.10 and CTLA-4-/- DO11.10 mice show comparable thymic maturation of T cells and lymphocyte numbers early in life (data not shown). At 6–8 wk of age, CTLA-4-/- DO11.10 mice show mild lymphadenopathy and splenomegaly. This may be due to activation of T cells expressing TCRs other than the DO11.10 TCR, or activation of DO11.10 T cells by cross-reactive ligands. In contrast to nontransgenic CTLA-4-/- mice, which die by 3–4 wk of age, the CTLA-4-/- DO11.10 mice survive for >16 wk, presumably because the transgenic TCR reduces the frequency of autoreactive T cells.
To compare the responses of DO11.10 wild-type and
CTLA-4-/- T cells, we purified
CD4+/KJ1–26+/L-selectinhigh
T cells from both strains. These T cells were activated in vitro with
OVA323–339 and APCs, and proliferation and
cytokine production were measured during primary and secondary
responses. DO11.10 wild-type and CTLA-4-/- T
cells showed comparable proliferation (Fig. 1
A) and, in most experiments,
similar IL-2 production during primary stimulation, and essentially no
IFN- was produced, as expected from naïve T cells (Fig. 1B). The only consistent difference between these cell
populations was that after 3–4 days of priming in vitro, the DO11.10
CTLA-4-/- T cells produced detectable amounts
of IL-4. This result suggests that naive T cells are capable of
producing IL-4 during primary responses to Ag, but are normally
prevented from doing so by CTLA-4.
|
, whereas CTLA-4-/-
DO11.10 T cells produced Th2 cytokines, IL-4, IL-5, and IL-10 (Fig. 2B). This bias toward Th2
development in cells that lack CTLA-4 was observed over a range of
peptide concentrations (0.1, 1, 10 µg/ml) during primary stimulation
(data not shown). Interestingly, in these recall responses the
CTLA-4-/- DO11.10 T cells proliferated more
than wild-type DO11.10 cells (Fig. 2A), suggesting that the
role of CTLA-4 in limiting T cell expansion is seen late during immune
responses.
|
Although the experiments with DO11.10 T cells suggest that CTLA-4 regulates Th2 differentiation, an alternative possibility is that some of these cells are activated in vivo by either environmental or endogenous Ag, and this may affect subsequent differentiation of the T cells. It is difficult to exclude such in vivo activation by unknown Ags. We have shown that stimulation of CD28 is critical for T cell activation in CTLA-4-/- mice, and that B7 antagonists prevent "spontaneous" lymphocyte activation and disease in CTLA-4-/- mice (17). More recently, we have demonstrated that breeding the CTLA-4-/- mice with mice lacking both B7.1 and B7.2 also completely prevents endogenous activation and disease (13). T cells from CTLA-4-/- B7.1/B7.2-/- mice have the phenotypic and functional characteristics of naive cells. We reasoned that studying the responses of CTLA-4-/- B7.1/B7.2-/- T cells to TCR cross-linking and wild-type APCs in vitro would provide an additional means of evaluating the functional capabilities of CTLA-4-/- T cells, without the confounding influence of in vivo activation.
CD4+ T cells were isolated from
CTLA-4-/- B7.1/B7.2-/-
mice and activated in vitro with anti-CD3 Ab and syngeneic
wild-type APCs. The primary and secondary responses of these cells were
compared with those of CD4+ T cells from mice
lacking only B7.1 and B7.2. As was seen with DO11.10 T cells, the
initial proliferation of these CTLA-4-/-
B7.1/B7.2-/- T cells was similar to that of
CTLA-4+/+ B7.1/B7.2-/-
cells. However, these CTLA-4-/- cells
proliferated more than the CTLA-4+/+ cells during
secondary stimulation (data not shown). Strikingly, the
CTLA-4-/- B7.1/B7.2-/-
T cells produced IL-4, even during primary stimulation in the presence
of wild-type APCs (Fig. 3A),
whereas the CTLA-4+/+
B7.1/B7.2-/- cells did not. Moreover, upon
secondary stimulation, these CTLA-4-/- cells
secreted much more IL-4 and much less IFN- than did
CTLA-4+/+ B7.1/B7.2-/-
cells (Fig. 3B). This differentiation into Th2 cells did not
appear to be solely determined by the strength of signal during the
priming, because IL-4 was produced by CTLA-4-/-
cells that had been primed over a range of anti-CD3 Ab
concentrations (from 1:500 to 1:10,000) during priming (data not
shown). Thus, when naive T cells lacking CTLA-4 are exposed to an Ag
analogue (anti-CD3 Ab) and costimulation, they differentiate into
Th2 populations.
|
To investigate whether the Th2 differentiation of
CTLA-4-/- T cells was due to IL-4 produced by
CTLA-4-/- T cells or an intrinsic property of
CTLA-4-/- T cells, we examined the consequences
of priming CTLA-4-/- T cells in the presence of
neutralizing anti-IL-4 Ab.
CD4+/KJ1–26+/L-selectinhigh
wild-type DO11.10 and CTLA-4-/- DO11.10 T cells
were primed with peptide Ag and APC in the presence of a saturating
concentration of anti-IL-4 Ab. During priming of
CTLA-4-/- DO11.10 T cells with 10 µg/ml
peptide for 5 days, the concentration of IL-4 in the supernatants was
0.07 ± 0.03 ng/ml, whereas in the presence of anti-IL-4 Ab no
IL-4 was detectable (detection limit for IL-4 ELISA was <0.005 ng/ml).
Therefore, IL-4 was effectively neutralized by the Ab. In both
wild-type and CTLA-4-/- DO11.10 T cells, the
presence of anti-IL-4 Ab during priming increased IFN-
production upon secondary stimulation (Fig. 4). However, the presence of
anti-IL-4 Ab during priming resulted in only a modest decrease in
IL-4 upon restimulation of CTLA-4-/- cells,
compared with CTLA-4-/- cells primed in the
absence of anti-IL-4. In secondary cultures, IL-4 was detected by
ELISA in supernatants of CTLA-4-/- DO11.10 T
cells that had been primed in the presence of anti-IL-4 (Fig. 4A). Furthermore, intracellular cytokine staining showed
IL-4 production by CTLA-4-/- DO11.10 cells that
had been primed in the presence of anti-IL-4 (Fig. 4B).
In addition, IL-4 mRNA was detected by RNase protection assays
(RPAs)4 of CTLA-4-/- DO11.10 cells
that had been primed in the presence of anti-IL-4 (data not
shown).
|
Anti-CD28 Ab stimulates Th2 differentiation in vivo in the absence of CTLA-4
The experiments described so far have investigated in vitro
responses of CTLA-4-/- T cells to peptide Ag or
TCR cross-linking and costimulation. We postulated that if CTLA-4 has
an essential role in regulating Th2 differentiation, then providing
mice lacking CTLA-4 with a CD28-mediated signal in vivo also might
induce a Th2 response. To test this, a stimulatory anti-CD28 Ab was
administered i.v. to CTLA-4-/-
B7.1/B7.2-/- mice or wild-type mice, lymph node
cells were harvested 19 days later, and IL-4 production was assayed
following restimulation of lymph node cells with anti-CD3 Ab. We
had previously shown that this anti-CD28 Ab (PV-1) produces a
lymphoproliferative phenotype in CTLA-4-/-
B7.1/B7.2-/- mice, but has no in vivo
proliferative effect in wild-type mice (13). As shown in
Fig. 5, exposure to this agonistic
anti-CD28 Ab in vivo induced IL-4 production in
CTLA-4-/- B7.1/B7.2-/-
cells, but not in wild-type cells. The
CTLA-4-/- cells made less IFN- than
wild-type mice (data not shown). The lack of an effect of anti-CD28
Ab in wild-type mice suggests that the B7-CTLA-4 interaction can
provide signals that limit CD28-mediated Th2 differentiation, even when
CD28 is triggered with a cross-linking Ab.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Both of these experimental systems show that CTLA-4 has a critical role in regulating Th2 differentiation. CTLA-4-/- T cells produced IL-4 even during primary stimulation and rapidly develop into almost pure populations of Th2 cells. This was seen not only in the DO11.10 strain, which is on a Th2-prone BALB/c background, but also in the 129Sv strain, in which T cells have a tendency to develop into Th1 cells when primed under "neutral" conditions. Furthermore, in vivo anti-CD28 administration led to striking Th2 differentiation in CTLA-4-/- B7.1/B7/2-/-, but not wild-type mice. Blocking IL-4 during priming of CTLA-4-/- T cells did not prevent Th2 development completely, whereas anti-IL-4 Ab inhibited Th2 responses of wild-type T cells (18). This may be because CTLA-4-/- T cells produce IL-4 whenever they encounter costimulation, i.e., either during primary or secondary stimulation. A number of studies have shown that the strength of the signal that a T cell receives contributes to the outcome of the T helper phenotype (19, 20). For this reason, we examined CTLA-4-/- T cells over a range of Ag doses. In all studies, we observed differentiation toward the Th2 phenotype.
The results described in this manuscript are consistent with a study using anti-CTLA-4 Ab, in which blockade of CTLA-4 during an staphylococcal enterotoxin B (SEB)-mediated immune response induced IL-4 production, especially by CD4+ cells (21). These results complement studies showing an important role for B7-CD28-mediated costimulation in Th2 development, because CD28-/- DO11.10 T cells and naive T cells stimulated with B7.1/B7.2-/- APC have impaired Th2 differentiation (11, 12).
The absence of CTLA-4 had no influence on initial proliferative responses and a relatively modest effect on proliferation upon restimulation. The modest effects of CTLA-4 on T cell proliferation are surprising in light of studies with Abs showing that CTLA-4 ligation limits T cell expansion very early after triggering (8, 9). In fact, our results suggest that CTLA-4 has an obligatory role in inhibiting T cell expansion late in immune responses. The kinetics of this effect are consistent with the kinetics of CTLA-4 expression, which typically increases 24–48 h after T cell activation in vitro (22).
We conclude from these studies that one of the major functions of CTLA-4 is to limit the magnitude of Th2 differentiation. When T cells recognize Ag on APCs, engagement of CD28 by B7 molecules promotes Th2 differentiation, whereas B7 binding to CTLA-4 blocks Th2 differentiation. The mechanism of these opposing effects of CD28 and CTLA-4 on cytokine profiles remains to be established. One potential mechanism could be that CTLA-4 competes with CD28 for B7 binding and therefore counteracts the Th2 differentiation induced by CD28 triggering. An alternative possibility is that CD28 transduces signals that directly activate the transcription of Th2 cytokine genes, and CTLA-4 inhibits these signals. We are currently comparing the effects of CD28 and CTLA-4 ligation on transcription factors that are known to bind to cytokine gene promoters (23) to identify the critical signals involved. Finally, these results raise the possibility that the skewed Th2 response of CTLA-4-/- T cells plays a role in the lymphoproliferative and infiltrative disease of CTLA-4-/- mice. Studies to define the roles of various cytokines in the disease of CTLA-4-/- mice, using cytokine antagonists and knockouts, are in progress.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 M.A.O., D.A.M., and S.D.B. contributed equally to this study.
3 Address correspondence and reprint requests to Dr. Arlene H. Sharpe, Brigham and Women’s Hospital, LMRC Room 512, 221 Longwood Avenue, Boston, MA 02115. E-mail address:
4 Abbreviation used in this paper: RPA, RNase protection assay.
Received for publication February 9, 1999. Accepted for publication June 28, 1999.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
ß T-cell-receptor transgenic system. Proc. Natl. Acad. Sci. USA 89:6065.ß transgenic model. J. Exp. Med. 182:1579.This article has been cited by other articles:
|
|
 |
|
  C. Hubeau, I. Apostolou, and L. Kobzik Targeting of CD25 and Glucocorticoid-Induced TNF Receptor Family-Related Gene-Expressing T Cells Differentially Modulates Asthma Risk in Offspring of Asthmatic and Normal Mother Mice J. Immunol., February 1, 2007; 178(3): 1477 - 1487. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Piconi, D. Trabattoni, M. Saresella, E. Iemoli, M. Schenal, A. Fusi, M. Borelli, L. Chen, A. Mascheri, and M. Clerici Effects of Specific Immunotherapy on the B7 Family of Costimulatory Molecules in Allergic Inflammation J. Immunol., February 1, 2007; 178(3): 1931 - 1937. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. H. Jaber, E. W. Cowen, L. R. Haworth, S. L. Booher, D. M. Berman, S. A. Rosenberg, and S. T. Hwang Skin Reactions in a Subset of Patients With Stage IV Melanoma Treated With Anti-Cytotoxic T-Lymphocyte Antigen 4 Monoclonal Antibody as a Single Agent. Arch Dermatol, February 1, 2006; 142(2): 166 - 172. [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]
|
|
|
|
|
|
R. J. Salmond, G. Huyer, A. Kotsoni, L. Clements, and D. R. Alexander The src Homology 2 Domain-Containing Tyrosine Phosphatase 2 Regulates Primary T-Dependent Immune Responses and Th Cell Differentiation J. Immunol., November 15, 2005; 175(10): 6498 - 6508. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. V. Parry, J. M. Chemnitz, K. A. Frauwirth, A. R. Lanfranco, I. Braunstein, S. V. Kobayashi, P. S. Linsley, C. B. Thompson, and J. L. Riley CTLA-4 and PD-1 Receptors Inhibit T-Cell Activation by Distinct Mechanisms Mol. Cell. Biol., November 1, 2005; 25(21): 9543 - 9553. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Sehra, D. Patel, S. Kusam, Z.-Y. Wang, C.-H. Chang, and A. L. Dent A Role for Caspases in Controlling IL-4 Expression in T Cells J. Immunol., March 15, 2005; 174(6): 3440 - 3446. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. van Wijk, S. Hoeks, S. Nierkens, S. J. Koppelman, P. van Kooten, L. Boon, L. M. J. Knippels, and R. Pieters CTLA-4 Signaling Regulates the Intensity of Hypersensitivity Responses to Food Antigens, but is Not Decisive in the Induction of Sensitization J. Immunol., January 1, 2005; 174(1): 174 - 179. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. P. Eggena, L. S.K. Walker, V. Nagabhushanam, L. Barron, A. Chodos, and A. K. Abbas Cooperative Roles of CTLA-4 and Regulatory T Cells in Tolerance to an Islet Cell Antigen J. Exp. Med., June 21, 2004; 199(12): 1725 - 1730. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. A. Yi, S. Hajialiasgar, and E. Chuang Tyrosine-mediated inhibitory signals contribute to CTLA-4 function in vivo Int. Immunol., April 1, 2004; 16(4): 539 - 547. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Pandiyan, D. Gartner, O. Soezeri, A. Radbruch, K. Schulze-Osthoff, and M. C. Brunner-Weinzierl CD152 (CTLA-4) Determines the Unequal Resistance of Th1 and Th2 Cells against Activation-induced Cell Death by a Mechanism Requiring PI3 Kinase Function J. Exp. Med., March 15, 2004; 199(6): 831 - 842. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Matsumoto, H. Inoue, T. Nakano, M. Tsuda, Y. Yoshiura, S. Fukuyama, F. Tsushima, T. Hoshino, H. Aizawa, H. Akiba, et al. B7-DC Regulates Asthmatic Response by an IFN-{gamma}-Dependent Mechanism J. Immunol., February 15, 2004; 172(4): 2530 - 2541. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. M. Rigby, T. Rouse, and E. H. Field Total lymphoid irradiation nonmyeloablative preconditioning enriches for IL-4-producing CD4+-TNK cells and skews differentiation of immunocompetent donor CD4+ cells Blood, March 1, 2003; 101(5): 2024 - 2032. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Steel and T. B. Nutman CTLA-4 in Filarial Infections: Implications for a Role in Diminished T Cell Reactivity J. Immunol., February 15, 2003; 170(4): 1930 - 1938. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Q. Tang, J. A. Smith, G. L. Szot, P. Zhou, M.-L. Alegre, K. J. Henriksen, C. B. Thompson, and J. A. Bluestone CD28/B7 Regulation of Anti-CD3-Mediated Immunosuppression In Vivo J. Immunol., February 1, 2003; 170(3): 1510 - 1516. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Fujimoto, H. Tsutsui, S. Yumikura-Futatsugi, H. Ueda, O. Xingshou, T. Abe, I. Kawase, K. Nakanishi, T. Kishimoto, and T. Naka A regulatory role for suppressor of cytokine signaling-1 in Th polarization in vivo Int. Immunol., November 1, 2002; 14(11): 1343 - 1350. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Schneider, D. A. Mandelbrot, R. J. Greenwald, F. Ng, R. Lechler, A. H. Sharpe, and C. E. Rudd Cutting Edge: CTLA-4 (CD152) Differentially Regulates Mitogen-Activated Protein Kinases (Extracellular Signal-Regulated Kinase and c-Jun N-Terminal Kinase) in CD4+ T Cells from Receptor/Ligand-Deficient Mice J. Immunol., October 1, 2002; 169(7): 3475 - 3479. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Aseffa, A. Gumy, P. Launois, H. R. MacDonald, J. A. Louis, and F. Tacchini-Cottier The Early IL-4 Response to Leishmania major and the Resulting Th2 Cell Maturation Steering Progressive Disease in BALB/c Mice Are Subject to the Control of Regulatory CD4+CD25+ T Cells J. Immunol., September 15, 2002; 169(6): 3232 - 3241. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. C. Henderson, M. M. Kamdar, and A. Bamezai Ly-6A.2 Expression Regulates Antigen-Specific CD4+ T Cell Proliferation and Cytokine Production J. Immunol., January 1, 2002; 168(1): 118 - 126. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. D. Brand, L. K. Myers, K. B. Whittington, K. A. Latham, J. M. Stuart, A. H. Kang, and E. F. Rosloniec Detection of Early Changes in Autoimmune T Cell Phenotype and Function Following Intravenous Administration of Type II Collagen in a TCR-Transgenic Model J. Immunol., January 1, 2002; 168(1): 490 - 498. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. M. Doyle, A. C. Mullen, A. V. Villarino, A. S. Hutchins, F. A. High, H. W. Lee, C. B. Thompson, and S. L. Reiner Induction of Cytotoxic T Lymphocyte Antigen 4 (CTLA-4) Restricts Clonal Expansion of Helper T Cells J. Exp. Med., September 24, 2001; 194(7): 893 - 902. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Mirshahidi, C.-T. Huang, and S. Sadegh-Nasseri Anergy in Peripheral Memory CD4+ T Cells Induced by Low Avidity Engagement of T Cell Receptor J. Exp. Med., September 10, 2001; 194(6): 719 - 732. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. S. Burr, S. L. Kimzey, D. R. Randolph, and J. M. Green CD28 and CTLA4 Coordinately Regulate Airway Inflammatory Cell Recruitment and T-Helper Cell Differentiation after Inhaled Allergen Am. J. Respir. Cell Mol. Biol., May 1, 2001; 24(5): 563 - 568. [Abstract] [Full Text]
|
|
|
|
|
|
G. Rossi, J. Sarkar, and D. Scandella Long-term induction of immune tolerance after blockade of CD40-CD40L interaction in a mouse model of hemophilia A Blood, May 1, 2001; 97(9): 2750 - 2757. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Gozalo-Sanmillan, J. M. McNally, M. Y. Lin, C. A. Chambers, and L. J. Berg Cutting Edge: Two Distinct Mechanisms Lead to Impaired T Cell Homeostasis in Janus Kinase 3- and CTLA-4-Deficient Mice J. Immunol., January 15, 2001; 166(2): 727 - 730. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. P. M. Broeren, G. S. Gray, B. M. Carreno, and C. H. June Costimulation Light: Activation of CD4+ T Cells with CD80 or CD86 Rather Than Anti-CD28 Leads to a Th2 Cytokine Profile J. Immunol., December 15, 2000; 165(12): 6908 - 6914. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
) and CTLA-4-/- cells
(plotted on the right, 
) show comparable
proliferation. Results are representative of six experiments.
B, Cytokines were measured by ELISA in culture
supernatants at 18, 30, 54, and 74 h after stimulation with 10
µg/ml peptide. IL-2, IFN-
