Species-restriction of rat lymphoid cell migration inhibitory factor

Migration inhibitory factor (MIF) was produced by lymphoid cells of Lewis rats in response to infection with Bacille Calmette Guérin (BCG), mixed lymphocyte reaction or concanavalin A stimulation. It was found that rat lymphokine-containing supernatants demonstrate a definite species specificity, in that MIF activity is observed only when rat indicator cells and not when guinea-pig indicator cells are used. A comparative study of MIF activities, using rat peritoneal exudate cells, revealed that all three methods stimulated MIF production by either spleen or lymph node cells. Only infection with BCG induced peripheral blood leukocytes to elaborate MIF. In all cases, rat MIF inhibited rat peritoneal exudate cells but not guinea-pig peritoneal exudate cells. Possible explanations for the species specificity of rat MIF including a role for receptor carbohydrate moieties and fibronectin are discussed.