Enhancement of the Primary Antibody Response to Particulate Antigens by Simple Lipids

Abstract

Intravenous injection of suspensions of triolein or ethyl stearate cause significant modification of the phagocytic activity of the RES in rats and in mice. When given in conjunction with particulate antigens these substances have been found to possess considerable adjuvant properties; however, adjuvance does not seem to be dependent upon the phagocytic activity of the RES at the time of antigen injection. The adjuvant effects of both lipids are dose-dependent and also influenced by the time of administration in relation to the antigen. Although both triolein and ethyl stearate elevate the primary antibody response if given 48 hr before the antigen, only triolein has marked adjuvant properties when given simultaneously with the antigen. Studies of the distribution of ⁵¹Cr-labeled antigen in rats and morphologic changes in spleen cell smears have suggested that two different mechanisms may operate in adjuvance due to these lipids. Of most significance has been the finding that, in animals treated simultaneously with triolein and antigen, a marked acceleration and augmentation of the early cellular events related to antibody production occurs in the spleen. The significance of these findings has been discussed in connection with their similarity to those of other workers using endotoxins and related substances as adjuvants.