Effects of immunological adjuvants on the mouse complement system--II. Anti-complementary effects of surface-active compounds.

The anti-complementary effects of the surface-active immunological adjuvants dimethyldioctadecylammonium bromide (DDA) and pluronic polyols L101 and L121 were investigated in the mouse system. All three adjuvants showed complement (C)-inactivating effects. DDA caused a time- and dose-dependent reduction of alternative pathway (AP) and overall C activity, which varied with the serum concentration. Polyols induced a preferential inactivation of the AP by a more direct mechanism. A rather general, causative relationship between anti-complementary and immunological adjuvant activities is suggested. This might involve interference with nonspecific elimination of antigen, counteraction of immunosuppression by terminal C components, and/or moderation of C3b-mediated reduction of Ia-expression, leading to a better antigen presentation.