CTLA-4 is an essential inhibitor of T cell immune responses. At steady state, most CTLA-4 resides in intracellular compartments due to constitutive internalisation mediated via a tyrosine based endocytic motif (YVKM) within the cytoplasmic domain. This domain is highly conserved in mammals suggesting strong selective pressure. In contrast, the C-terminal domain varies considerably in non-mammal...

The costimulatory molecules B7-1 and B7-2 regulate T lymphocyte activation by delivering activating signals through CD28 and inhibitory signals through cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). The importance of CTLA-4-mediated inhibition was demonstrated by the uncontrolled T cell activation and lymphoproliferative disease that develops in CTLA-4-deficient (-/-) mice. To examine th...

CTLA-4 is thought to inhibit effector T cells both intrin-sically, by competing with CD28 for B7 ligands, and ex-trinsically, through the action of regulatory T cells (Tregs). We studied in vivo responses of normal and CTLA-4–deficient Ag-specific murine effector CD4 + T cells. We directly demonstrate that effector T cell-restricted CTLA-4 inhibits T cell responses in a cell-extrinsic manner. C...

Multiple sclerosis (MS), a chronic inflammatory demyelinating disease of the central nervous system is believed to have a T cell-mediated autoimmune etiology. The cytotoxic T lymphocyte antigen 4 (CTLA-4) gene is a strong candidate for the involvement in autoimmune diseases. To examine the genetic association of the CTLA-4 gene locus with MS, in a case-control design, we analyzed (-318 C/T) sin...

Cytotoxic T lymphocyte antigen-4 (CTLA-4) is an inhibitory receptor on T cells essential for maintaining T cell homeostasis and tolerance to self. Mice lacking CTLA-4 develop an early onset, fatal breakdown in T cell tolerance. Whether this autoimmune disease occurs because of the loss of CTLA-4 function in regulatory T cells, conventional T cells, or both is unclear. We show here that lack of ...

CTLA-4 gene is one of the strongest locus of genetic susceptibility to autoimmune thyroid diseases. The aim of the present study was to investigate surface expression of CTLA-4 on peripheral T cells in homozygotes AA and GG at position +49 of CTLA-4 gene in children with Hashimoto's thyroiditis and in healthy controls. Blood samples were obtained from 100 children: 45 with Hashimoto's thyroidit...

Expression of the CTLA-4 gene is absolutely required for immune homeostasis, but aspects of its molecular nature remain undefined. In particular, the characterization of the soluble CTLA-4 (sCTLA-4) protein isoform generated by an alternatively spliced mRNA of CTLA4 lacking transmembrane-encoding exon 3 has been hindered by the difficulty in distinguishing it from the transmembrane isoform of C...

To examine the relationship between cytotoxic T lymphocyte antigen-4 (CTLA-4) expression and esophageal carcinoma prognosis, CTLA-4 expression was immunohistochemically detected in paraffin-embedded primary tumor specimens from 158 patients with esophageal cancer. CTLA-4 was detected in the cytoplasm and cell membranes of esophageal cancer cells and in interstitial lymphocytes. In univariate an...

CD8+ cytotoxic T lymphocytes contribute to viral and autoimmune myocarditis and cardiac allograft rejection. The role of cytotoxic T-lymphocyte-associated antigen (CTLA)-4 as a negative regulator of CD4+ T cells is well defined, yet CTLA-4 regulation of CD8+ T cells is less clear. We studied CTLA-4 regulation of cytotoxic T lymphocytes in a transgenic model of CD8+ T-cell-mediated myocarditis. ...

Knockout and blocking studies have shown a critical role for CTLA-4 in peripheral tolerance, however, it is unknown whether augmenting CTLA-4 expression actually promotes tolerance. Here we demonstrate a specific and requisite role for CTLA-4 and its up-regulation in tolerance through anti-CD45RB. First, long-term murine islet allograft survival induced by anti-CD45RB is prevented by CTLA4-Ig, ...