Defect in B cell function in HTLV III/LAV positive hemophilia patients.

The capacity of the peripheral blood lymphocytes (PBL) to generate an antibody response in vitro T cell-dependent antigen ovalbumin was studied in 12 severe hemophilia patients who were otherwise in good health. PBL from four of 12 patients were not capable of generating such a response after stimulation in vitro, whereas all controls were normal. This negative plaque-forming cell (PFC) response coincided with the presence of antibodies directed toward human T-lymphotropic virus III/lymphadenopathy-associated virus (HTLV-III/LAV). Only one patient with antibodies against HTLV-III/LAV had a normal PFC response. The negative PFC response was not due to a deficient T helper cell activity, nor to an excessive T suppressor cell function. However, in the peripheral blood of these four patients, the presence of activated B cells that are refractory to antigen-specific T helper cell signals and secrete specific antibodies spontaneously could be demonstrated. Most of the patients showed a hyperimmunoglobulinemia. No correlation between the T4/T8 ratio and the level of the PFC response was demonstrable. From the data obtained in these investigations we raise the hypothesis that infection with HTLV-III/LAV in hemophilia patients will lead to in vivo (pre)activation of B cells that results in unresponsiveness or decreased response to antigen-specific signals.