Cloning of Functional T Lymphocytes

Abstract

While there is general agreement that T lymphocytes play a central role in the immunological effector mechanisms operative in viral diseases, the diversity of T lymphocytes has made it difficult to unravel the molecular and cellular basis of these mechanisms. This diversity is accounted for by the existence of multiple, distinct lymphocyte subsets that are responsible for a variety of immunological functions. Thus, in addition to cytolytic, helper, and suppressor activities, effector T lymphocytes release soluble, biologically active mediators known as lymphokines. While it is generally accepted that a single effector T cell cannot perform all these functions, there is still much uncertainty as to the number of functionally distinct subsets. A direct approach to this question would be to examine the function(s) of individual effector T cells. Unfortunately, with the exception of cytolytic T lymphocytes (CTL), there are no single cell assays available for functional T cells. Therefore, it has been necessary to turn to the more practical approach of determining the function(s) of clonal progeny of individual effector T cells. Such an approach has been suggested by the recognition that effector T cells, unlike their B cell counterparts (i.e., plasma cells), are not necessarily end cells, but can undergo extensive proliferation in vitro in the presence of an adequate source of T-cell growth factor (TCGF), also designated Interleukin 2 (IL-2) (reviewed in [1]).