Basic components of the immune system part 22

T cells and their receptors

Each T cell is also committed to a given antigen and recognizes it by one of two T cell receptors. They may have T cell receptors composed of gamma (γ) and delta (δ) chains or T cell receptor composed of another heterodimer of alpha  (α) and beta (β) chains. These T cell receptor  are  associated with a group of transmembrance proteins an the CD3 molecule, which takes the antigen recognition signal inside the cell. Signal transduction via the CD3 complex is regulated by a series  of kinases, which are associated with the tails of the CD3-TCR complex  and regulate phosphorylation. Deficiencies or blocks in the T-cell signaling pathways either at the cell-surface complex  or at the level of the kinases may result in various forms of immunodeficiency. Two other important antigens present on T cell receptor cells recognize histocompatibility antigens.