Enhancement of Immune Responses to Polysaccharide Antigens Using 8-Mercaptoguanosine.

8-Mercaptoguanosine (8sGuo) is an adjuvant that can be used to enhance the in vivo response of mice to polysaccharide antigens. This enhancement of the immune response is observed in all of the IgG subclasses examined, IgG1, IgG2, and IgG3. Most interestingly injection of this adjuvant restores the responses of nonresponder immune defective CBA/N mice to TNP-Ficoll the prototype polysacharide antigen we use in these experiments. Concomitant administration of this adjuvant together with TNP-Ficoll also enhanced the antibody responses of low responder neonatal mice to this antigen. Since our results suggested that this immune adjuvant was being rapidly metabolized in vivo we determined whether continuous injection of this adjuvant was more effective than a single dose. Our results indicate that injection of 8sGuo on three consective days was significantly more effective in enhancing anti-TNP-Ficoll responses than administration on one day only. We have determined from in vitro experiments that 8sGuo is exerting its predominant effect on activated and not resting B cells. Taken together our data suggest that this immune adjuvant will serve as a useful tool to investigate the regulatory controls of immune responses to polysaccharide antigens in normal and immune defective mice as well as in neonatal mice.