AbstractThe in vitro effect of IFN-a on lymphocyte transformation and specific immune response against Brucella antigens was studied in 33 patients with chronic brucellosis and 10 normal controls. The following immunologic in Aditro tests were applied: PHA activated lymphocyte transformation test using Bromodeo-xyuridine and a monoclonal antibody in the presence and abscence of 50 and 100 IU IFN Alpha-2b and leukocyte migration inhibition test against Brucella antigens in the presence and abscence of 100 and 500 IU of IFN Alpha-2b. Patients were further divided to 2 subgroups according to a positive or negative migration inhibition test.Our results showed that T lymphocyte transformation was similar in patients and controls and that the addition of 50 IU IFN resulted in a significant increase of transforming cells whereas in the concentration of 100 IU IFN only anergic patients and controls responded positively. IFN also resulted in a significant leukocyte migration inhibition only in anergic patients and controls. These findings suggest that the chronic infection is not due to a generalized cellular immunodeficiency state and that IFN Alpha-2b might be a promising therapeutic approach in anergic patients.