Migration enhancement factor: a new lymphokine.

Production of human migration inhibitory factor by lymphocytes exposed to antigen was studied at intervals over a 7-day period. Migration inhibitory factor was measured by an agarose gel method, with buffycoat leukocytes as indicator cells. Lymphocyte supernatants from 7-day cultures consistently showed migration inhibitory factor activity; by contrast, enhancement of migration was frequently noted when effector cells were exposed to supernatants from 2- to 5-day cultures. Enhancement activity was manifested either by enhanced migration or by a sequential reduction in inhibitory activity consistent with a factor opposing the action of migration inhibitory factor. When supernatants were subjected to polyacrylamide gel electrophoresis, enhancement activity was regularly found in the beta-globulin region and migration inhibitory factor in the albumin fraction of the gel. The enhancement activity was heat-stable and nondialyzable. These findings characterize a hitherto unreported lymphokine, migration enhancement factor.