Effects of interferon gamma and saponin on lymphocyte traffic are inversely related to adjuvanticity and enhancement of MHC class II expression

Abstract

Interferon gamma (IFN-gamma) is an effective immunological adjuvant when mixed with vaccines prior to injection, but the way in which it exerts this effect has been unclear. Because some adjuvants have been shown to affect lymphocyte traffic, and interferons have been shown to have effects on lymphocyte homing molecules, we examine in this study the effects of IFN-gamma and the potent adjuvant saponin on lymphocyte traffic, and show that both of these adjuvants increase lymphocyte homing to an injection site in mice. We have then compared effects on lymphocyte traffic and on MHC class II expression with adjuvant effects in different mouse strains. Effects on lymphocyte traffic were the inverse of adjuvant effects in different strains, however both materials enhanced MHC class II expression, and this enhancement corresponded with adjuvanticity in different strains of mice. A possible explanation for the negative effect of lymphocyte homing may be that the vast majority of T cells homing to the injection sites in response to both IFN-gamma and saponin were of the CD8+ (suppressor/cytotoxic) phenotype.