Enhancement of antibody synthesis by 6-mercaptopurine.

The administration of 6-MP to rabbits led to either suppression or enhancement of antibody production, depending on when the drug was given in relation to the antigenic challenge. Maximum enhancement of antibody synthesis was found when a small dose of BGG was administered 5 days after the last dose of a 1 wk course of 6-MP. There were no indications that the macrophage system or immunological memory was affected in animals with augmented antibody synthesis. It was proposed that enhancement of antibody production by 6-MP was due to nucleic acids released from cells killed or injured by the drug. It was suggested that lymphocytes incorporating these nucleic acids were transformed into specialized cells capable of direct and immediate stimulation by antigen and lacking immunological memory (hemocytoblasts). A relatively small dose of antigen was apparently capable of stimulating all the hemocytoblasts representing a given clone) with the result that large amounts of antibody rapidly appeared in the serum.