T-cell populations with different functions

Abstract

VARIOUS functions have been ascribed to thymus-derived (T) cells, including the ability to synergise with B cells in antibody responses¹ and with T cells in the generation of effector functions (refs 2–4 and H. Cantor and E. Simpson, unpublished), cytotoxic activity⁵, and regulator or suppressor activity^6,7. T-cell subpopulations, defined by criteria such as quantity of cell surface θ antigen, homing characteristics (H. Cantor and E. Simpson, unpublished) and sensitivity to the effects of adult thymectomy and anti-thymocyle serum^2,8, have been described, but the functions of given subpopulations are still unclear. It seems likely, by analogy with B-cell differentiation and commitment to antibody class, that T cells become committed to certain functions during differentiation. In the absence of markers for individual T cells and their products or functions, analysis of cell populations and their activities provide an approach to this question. Experiments of this type have dissociated helper and cytotoxic activity^9,10, and the ‘unmasking’ of nonspecific suppressor T cells was reported to follow the culture of helper cells with specific antigen¹¹. We have now dissociated helper activity and cytotoxic activity directed towards a given alloantigen following either in vitro or in vivo immunisation. We also found that nonspecific suppressor T cells arise during in vitro culture.