Expression and functional significance of CTLA-4, a negative regulator of T cell activation

• Authors: A. Kosmaczewska , L. Ciszak , D. Bocko , I. Frydecka
• Languages of publication: EN

Abstracts

EN

The generation of an effective immune response involves antigen-specific T cell expansion and differentiation of effector function. T cell activation requires at least two distinct signals, including signaling via the Ag-specific TCR and a costimulatory pathway. Antigen stimulation of T cells can lead either to a productive immune response characterized by proliferation, differentiation, clonal expansion and effector function or, in absence of appropriate costimulation, to a state of long-lasting unresponsiveness termed anergy. Anergic T cells fail to proliferate and secrete cytokines in response to secondary stimulation. The interaction between costimulatory molecule CD28 on T cells with members of the B7 family on APC results in upregulation of T cell proliferation, cytokine production and induces the expression of the anti-apoptotic protein Bcl-xl. Based of those findings, the two-signal requirement model for T cell activation is today generally accepted. The negative regulatory mechanisms during T cell activation are not well understood, but they are crucial for the maintainance of lymphocyte homeostasis. For several years the functional role of the enigmatic CD28 homologue CTLA-4 (cytotoxic T lymphocyte antigen-4) in T cell activation has been both obscure and conteroversional. CTLA-4 was initially proposed to provide a costimulatory signal in conjunction with TCR/CD3 signaling. Today we know that CD28 and CTLA-4 molecules may have diametrically opposed functions: signaling via CD28, in conjunctive with TCR, is required for T cell activation, while signaling via CTLA-4 is a negative signal that inhibits T cell proliferation. How the T cell integrates signals through the TCR/CD3 complex, CD28 and CTLA-4 to initiate, maintain and terminate antigen-specific immune response is actually not fully clarified. In this review, we will focus on the emerging role of CTLA-4 as a negative regulator of T lymphocyte activation and its role in dynamic interplay of activatory and inhibitory signals.

Keywords

EN

CTLA-4; NEGATIVE REGULATION; T CELL

Discipline

• IMMUNOLOGY: IMMUNOLOGY

• Publisher: Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences
• Journal: Archivum Immunologiae et Therapiae Experimentalis
• Year: 2001
• Volume: 49
• Issue: 1
• Pages: 39-46

Contributors

author

A. Kosmaczewska

author

L. Ciszak

author

D. Bocko

author

I. Frydecka

• Document Type: REVIEW
• Publication order reference: A. Kosmaczewska, Laboratory of Immunopathology, Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland,