TEMPORAL RELATIONSHIPS AND IL-2 DEPENDENCY OF PROLACTIN-INDUCED LYMPHOCYTE-PROLIFERATION

Recombinant preparations of human prolactin (hPRL) and interleukin 2 ( hIL-2) as well as monoclonal antibodies to these growth factors were u sed to study the synergistic interaction of PRL and IL-2 in Nb2 rat ly mphoma lactogen-dependent cells. It was shown that IL-2 stimulated Nb2 cell proliferation in lactogen-free culture medium. Experiments with short-term exposure to growth factor demonstrated that PRL was require d only during the initial 12 h of incubation while IL-2 was mitogenic regardless of the time it was added. Antibody to IL-2 partially inhibi ted both PRL- and IL-2-induced proliferation whereas antibody to PRL s ignificantly decreased PRL but not IL-2-induced proliferation. These f indings suggest that the complete mitogenic effect of PRL on Nb2 cells requires stimulation of IL-2 production.