The Role of Adhesion Molecules in the Anti-Viral T-cell Response

Adhesion molecules in T-cell receptor

Abstract

Adhesion molecules or receptor play key role in many processes involving cellular immunity that included haematopoiesis , migration , activation and finally apoptosis . They are mainly surface glycoproteins and variation among them is mainly due to different pattern of glycosylation . Adhesion molecules play a central role in T cell activation by providing initial temporary attachment of TCR and Antigen bearing MHC on APC . It was clearly demonstrated by various studies where complete inhibition of cellular immunity was observed in response to Monoclonal antibody against many of

these adhesion molecules . Cytotoxic CD8 T cells mediated immunity play a key role in viral infection control . It exerts it effect by close cellular interaction with viral infected target cells . Adhesion molecules play a crucial role in driving the effector T cell towards viral infected target cell as well as to establish interaction between TCR and APC . This article briefs the function and properties of some vital adhesion molecules such as LFA-1 ICAM and VLA-4 . Further , research carried out to assess the role of adhesion molecules in T-cell receptor is also summarized

Thymus derived (T ) lymphocytes are important regulatory and effectors cells in immune responses . The specificity of cellular immunity is mediated by T cell receptor-CD3 complex interacting with foreign antigen represented by MHC molecule (BARBARA E , 1988 Activation of T cells leads to functioning of T Cells where it produces various cytokines and cell lyses . In general , CD4 T cells act as helper cells by producing different effectors molecules after interacting with antigen bearing APC cells , whereas CD8 cell directly exert it 's effect by killing the antigen bearing APC cells . Activation and generation of effectors T cells are mediated by TcR-CD3 complex but there are several other surface molecules that play a significant role in immune response and T cell adhesion to APC . Similarly , they have significant role in cell migration , homing and recirculation . Some recent reports indicate the role of these molecules in T cell activation and differentiation . Among many are LFA-1 , CD2 , CD4 , and CD8 . Each of these molecules interact with it ligands for example LFA-1 binds to ICAM-1 while LFA-3 bind to CD2 etc (BARBARA E , 1988

LFA-1

The LFA-1 molecule is member of a family of three related proteins found on lymphoid and myeloid cells having common Beta subunits of MW 95000 . They are non covalently associated with a unique alpha subunit . Two other members of LFA-1 families are CR3 and p150 LFA-1 molecules are widely distributed on all thymocytes , T cells , B cells , and natural killer cells . Identification of LFA-1 was done when monoclonal antibodies against it was used to inhibit cytotoxic T cell mediated killing and later on it was found to be key molecules which helps in TCR-APC interaction as adhesion molecules . Similar observation are made where anti LFA- 1 monoclonal antibody inhibits spontaneous aggregation or homotypic adhesions between EB virus mediated activated T cells . This clearly indicates the role of LFA-1 in strengthening the intersection . Any abnormality in expression of...