Abstract
The presence of leucocyte migration inhibition factor (LIF) in supernatants from apparently antigen- and mitogen-free cultures of mononuclear cells (MNC) was studied. MNC were eluted from inflamed synovial tissue or isolated from blood. Untreated supernatants, supernatants in which any LIF had been inactivated, and culture medium were compared in their ability to affect the migration of homologous polymorphonuclear leucocytes. LIF was released by synovial tissue MNC from all of the 9 patients studied, consisting of 5 patients with rheumatoid arthritis, 2 with psoriatic arthropathy, and 2 with juvenile rheumatoid arthritis. Blood MNC of the patients and of 8 healthy blood donors did not release LIF. When synovial tissue MNC supernatants from 2 patients were examined, LIF activity increased as time of incubation was extended. In at least 2 synovial tissue MNC supernatants in which LIF had been inactivated a migration enhancement activity was revealed.