[Modification of the immune reaction by antigen-immunosuppressive-agent conjugates. IV. Studies on the specific suppression of humoral immune response in guinea pigs by antigen-immunosuppressive-agent conjugates].

Bovine gamma globulin (BGG) antigens were modified by the binding of 6-mercaptopurine and toluyl residues, and their influence on the humoral immune response in guinea pigs was investigated. The antigen-immunosuppressive agent-conjugates (AIC) were different, depending on the method used for their preparation and the number of coupled residues per one molecule of BGG. Conjugates denoted as MPI-n-BGG were prepared by special chemical binding of corresponding thioisocyanates. MPII-n-BGG were synthetized by acetylation, and MPIII-n-BGG conjugates, by reductive alkylation. Pretreatment of guinea pigs with MPIII-19-BGG, MPII-16-BGG resulted in a stimulatory effect on the subsequent humoral immune response induced by BGG application. A significant suppressive influence was detectable if the animals had been pretreated with MPII-6-BGG and MPI-26-BGG. MPI-13-BGG and MPI-36-BGG had no effect on the later induced anti-BGG antibody formation. The immune response against a second antigen (human serum albumin) was not influenced by this kind of pretreatment of the animals. Therefore it seems justified to conclude that both stimulatory and suppressive effects seen here were antigen specific and that both the method for chemical modification and the number of coupled 6-MP residues are very important for their effectivity.