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in antibody responses1 and with T cells in the generation of effector functions (refs 2–4 and H. Cantor and E. Simpson, unpublished), cytotoxic activity5, and regulator or suppressor activity6,7. 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defined by criteria such as quantity of cell surface θ antigen, homing characteristics (H. Cantor and E. Simpson, unpublished) and sensitivity to the effects of adult thymectomy and anti-thymocyle serum2,8, have been described, but the functions of given subpopulations are still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 activity9,10, 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.