The effect of a water soluble adjuvant on the immune response to synthetic polypeptides.

The effect of a water soluble adjuvant (WSA) extracted from mycobacteria on the immune response to synthetic polypeptides has been studied in rabbits and inbred mice. WSA increased the antibody response of rabbits to the synthetic polypeptide poly(Tyr,Glu)-poly(DLAla)--poly(Lys) designated (T,G)-A--L when injected together with either incomplete or complete Freund's adjuvants (FIA or FCA). As compared to the respective controls, the effect of WSA was more pronounced when injected with FIA. No detectable antibody titre was observed in rabbits immunized with (T,G)-A--L and WSA administered in an aqueous medium. WSA had no enhancing adjuvant effect on the antibody response of C3H.SW high responder mice to (T,G)-A--L when given either with FIA or with FCA. However, the antibody titres of C3H/HeJ and SJL low responder mice to (T,G)-A--L were increased by WSA when injected in combination with FIA or FCA. The immune responses of mice to two other synthetic polypeptides poly(Phe,Glu)-poly(DLAla)--poly(Lys), designated (Phe,G)-A--L, and poly-(Tyr,Glu)-poly(Pro)--poly(Lys), designated (T,G)-Pro--L, were not affected by the addition of WSA. Thus, WSA "corrects" selectively the genetic defect of low responder mice to synthetic antigens.