ROLE OF GAMMA-DELTA T-CELLS IN THE IMMUNE-RESPONSE AGAINST TUMOR-CELLS

T lymphocytes recognize antigen via a clonally distributed T cell receptor (TCR) heterodimer. Most T cells carry a TCR composed of an alpha and a beta chain. 1-10 % of CD3(+) peripheral blood T cells express a gamma delta TCR instead of;the conventional alpha beta TCR. gamma delta T-cells produce a variety of cytokines and possess strong cytolytic activity. A small hut significant percentage of gamma delta T cells is present among tumor-infiltrating lymphocytes in most solid tumors analysed. gamma delta T-cell lines or clones derived from tumor-infiltrating lymphocytes exert strong MHC-independent cytotoxicity and, in some instances, preferentially kill autologous tumor cells. The target antigens recognized by gamma delta T cells on tumor cells are generally unknown; heat-shock proteins are, however, likely candidates in some cases. The available evidence indicates that gamma delta T cells may contribute to the cellular immune response against tumor cells.