Specific lymphocyte stimulation by purified, heat-inactivated hepatitis-B antigen.

The ability of purified, heat-inactivated hepatitis-B antigen (HBAg) to stimulate sensitized lymphocytes in vitro was investigated with the lymphocyte stimulation test on lymphocytes from three groups of individuals. Stimulation was minimal in the lymphocytes of two out of 15 normal controls, whereas lymphocytes from nine out of 12 patients who had recovered from hepatitis B showed stimulation, as did lymphocytes from five out of 12 laboratory technicians who had been regularly exposed to HBAg but who had no history of hepatitis or signs of it in the previous two years. No differences were observed in the responses to phytohaemagglutinin of lymphocytes from persons in the three groups. HBAg and HBAg inactivated by heat were shown in immunodiffusion to be immunologically identical. Inactivated HBAg stimulated antibody production in guinea-pigs. These findings suggest that not only humoral but also cell-mediated immunity might be induced by vaccination with purified, heat-inactivated HBAg.