The role of macrophages in promoting the antibody response mediated by liposome-associated protein antigens.

The effect of the in vivo depletion of macrophage function on the plaque-forming cell (PFC) response to liposome-associated bovine serum albumin (LSM-BSA) in mice was investigated. Suppression of macrophage activities was accomplished by the intraperitoneal administration of carrageenan (CGN), a sulphated polygalactose which selectively inhibits macrophage function without interfering with the reactivity of T- and B-lymphocytes. Thus, control animals injected with CGN were found to give a significantly suppressed PFC response to sheep red blood cells, a macrophage-dependent antigen, but not to E. coli lipopolysaccharide, a macrophage-independent antigen. The pretreatment of experimental animals with CGN virtually abolished their antibody response to LSM-BSA in terms of the circulating anti-BSA antibody titers and the BSA-specific PFC response. These results provide evidence to substantiate an obligatory role of macrophages in inducing the humoral response to liposome-associated protein antigens.