Differences in immune functions between human T-lymphotropic virus type I carriers and patients with adult T-cell leukemia/lymphoma.

A variety of immunologic tests were compared between human T-lymphotropic virus type I (HTLV-I) carriers and patients with adult T-cell leukemia/lymphoma (ATL). The mitogenic responses of the lymphocytes to concanavalin A and phytohemagglutinin were depressed in the ATL patients but not in the carriers, while the response to pokeweed mitogen in the carriers and ATL patients was depressed compared to the HTLV-I-seronegative controls. A positive tuberculin reaction in the carriers was as frequent as in the controls, but less frequent in the ATL patients. A marked inhibition of the intracellular multiplication of Legionella pneumophila was observed within the monocytes isolated from the carriers, but not in the ATL patients or the normal controls. These results indicate that the ATL patients have severe immunodeficiency, while the HTLV-I carriers have some activation of anti-microbial activity in monocytes although they are somewhat immunosuppressed.