Thymopentin as adjuvant to hepatitis B vaccination. Results from three double-blind studies.

The influence of adjuvant thymopentin therapy on the effect of vaccination with HB-Vax was investigated in three independent double-blind studies in which three different time/dose schedules of the adjuvant therapy were used. The first study was conducted with 30 hemodialyzed patients who had previously been non- or hyporesponders. Forty and 26 nonvaccinated hemodialyzed patients were chosen for the two additional studies. A 50-mg dose of thymopentin or placebo was administered subcutaneously in all studies. In one study, in which only one adjuvant injection was administered simultaneously with each vaccine injection, thymopentin inhibited the antibody response. On the contrary, in the other two studies, in which three injections of adjuvant were administered during the week following the vaccination (in one of these studies three injections were also given before the vaccination), no difference in the effect of vaccination was observed in patients on either placebo or thymopentin. Comparison of the results of the present studies with those of earlier observations emphasizes the importance of time/dose schedules of adjuvant therapy in vaccination.