Clonal Analysis of Human T Lymphocytes Inducing B Cell Growth

Abstract

The central role of T lymphocytes in the control of antibody responses has been known since long time. Nevertheless, only during the last few years major progresses have been made towards 1) the understanding of the functional and pheno-typic characteristics of T cells which influence B cell growth and differentiation, 2) The nature of soluble factors involved in signalling between T and B lymphocytes. 3) The stages and mechanisms involved in B cell activation, proliferation and differentiation (1). For the most part, this favorable situation can be traced to the merging of new technologies. On the one hand, the use of monoclonal antibodies has provided omogeneous reagents for the unambiguous definition of the pheno-typic characteristics of T cell subsets and clones (2) and of B cells at different stages of activation. In addition, mAbs specific for some lymphokines and/or their cell surface receptors allowed a more precise definition of the involvement of these mediators in B cell growth or differentiation (3–6). At the same time, molecular ingeneering techniques provided scientists with some lymphokines in recombinant form (7): it thus became evident that several different activities could be attribued to single lymphokines. In addition, rapid advances in flow microfluorometry have provided a precise and objective means to quantify given surface markers and the extent to which the marker is expressed. Finally the improvement of T cell cloning techniques made it possible to grow virtually all T lymphocytes, thus allowing to identify both frequencies and subset distribution of T cells responsible for B cell proliferation and differentiation.