Functional maturation of thymocytes: recruitment of helper cells in the humoral immune response to SRBC in vitro by recombinant interleukin 1 (Il-1).

In this report we demonstrated that recombinant human interleukin 1 alpha (Il-1) can directly promote generation of helper cells in the humoral immune response to SRBC in vitro from their intrathymic precursors. Using negative elimination of thymocytes by means of monoclonal antibodies directed against thymocyte antigens L3T4, lyt 2 and CD3 with complement, we showed that Il-1 interacted with L3T4-, lyt 2-, CD3- T cell precursors. We found, in addition, that recombinant Il-1 induced in these cells expression of L3T4, lyt 2, CD3 and T cell receptor (TCR). The results presented in this communication are compatible with the view that Il-1 is responsible for the recruitment of functional T cells in the afferent phase of the immune response.