Ia dependent lymphokine production in the syngeneic mixed lymphocyte response

We have shown that Interleukin 2 (IL-2) is produced in the murine syngeneic mixed lymphocyte response (SMLR) by T cells from both young thymus and adult spleen responder populations. We extend these findings in this report by showing that: 1) IL-2 production is the function of an Lyt 1+, Lyt-2-, Qa-2,3+, Qa-5- and Ia- T cell; 2) Similar to IL-2 elicited following alloantigen or mitogen stimulation, it peaks at day 2-3 of culture in both thymic and splenic SMLR; 3) The presence of the SMLR/IL-2-producing cell in thymus is a transient event, disappearing by 4 weeks of age; 4) The production of cytotoxic T lymphocyte (CTL) helper factor activity in primary SMLR is under the same Ia control as is IL-2 production and 5) That significant levels of interferon (IFN) are produced in the splenic SMLR. These findings support our contention that the SMLR represents an in vitro model of an in vivo mechanism for the production of IL-2, and that such a mechanism may play a role in T cell differentiation.