Specific MIF release by rat lymphocytes following incubation with syngeneic anti-tumor “Immune” RNA

Other investigators have previously shown that normal nonimmune lymphoid cells, after incubation with “Immune” RNA, will release MIF when these cells are incubated with the specific antigen used to immunize the RNA donor. This conversion can be detected with the macrophage migration inhibition assay. These observations have been confirmed in a system involving the transfer of immune response to tumor associated antigens with syngeneic “Immune” RNA. Syngeneic “Immune” RNA was extracted from the spleens of Fischer 344/N rats bearing growing transplants of one or another of two syngeneic chemically induced sarcomas. Normal, nonimmune Fischer 344/N spleen cells were incubated with these RNA preparations. When these RNA-incubated spleen cells were exposed to solubilized antigens from that particular tumor used to immunize the RNA donor, MIF was released. RNAse treatment of the “Immune” RNA abrogated the response, while DNAse or pronase treatment did not.