Migration inhibition factor activity in sera of patients with chronic lymphatic leukemia.

Migration inhibition factor (MIF) activity, expressed as a migration index, was studied in the sera of 48 chronic lymphatic leukemia (CLL) patients and 48 healthy controls. MIF activity was detected in the sera of 50% of the CLL patients. The medical condition of patients in advanced clinical stages (III and IV) and with detectable MIF activity was more stable (after 18-mo follow-up) than was that of the patients in advanced stages but without detectable MIF activity. No relationship was found between the clinical stage of the disease, absolute lymphocyte count, and MIF activity.