An indirect assay for canine leukocyte migration inhibitory factor (LIF): demonstration of its species specificity.

An indirect assay in agarose-gel was developed to measure secretion of leukocyte migration inhibitory factor (LIF) by canine lymphocytes. Supernatants from cultures of mitogen- or alloantigen-stimulated canine peripheral blood lymphocytes were assayed for LIF activity using purified granulocytes as indicator cells. Canine LIF activity could be detected provided either autologous or allogeneic canine granulocytes were used as indicator cells. In contrast, canine LIF uniformly failed to inhibit the migration of human granulocytes. Likewise, human LIF inhibited the migration of human but not canine granulocytes in this assay. The data indicated that this species specificity could be due to differences in the structures of LIF receptors on canine and human granulocytes.