Immunoregulation by mouse T-cell clones. II. The same H-Y-specific T helper clone can provide help for the generation of cytotoxic lymphocytes and antibody-secreting cells.

Mouse H-Y-specific and I-Ab restricted T-cell clones have been established and compared for their helper effects in the differentiation of both T and B lymphocytes. The results demonstrate that three individual T-cell clones and one subclone could help in the antigen-driven induction of cytotoxic lymphocytes (CTL) from their precursor cells (CTL-P), and were able to activate B cells to develop into antibody-secreting cells (PFC) in the presence of SRBC, provided the cloned T cells were restimulated by H-Y antigen on antigen-presenting cells. In addition, antigen or lectin could induce the same H-Y-specific T-cell clones to secrete factor(s) expressing helper activities similar to that of the cloned T cells. Furthermore, it is shown that the T cell-derived soluble mediator(s) was distinct from T-cell growth factor (TCGF) and from immune interferon (IFN-gamma). The data reveal a new type of T cell with helper potential for the activation of CTL-P and B lymphocytes, and suggest the existence of distinct T helper cells which can provide help for both cytotoxic and antibody responses by virtue of different lymphokine activities.