Stimulation of liposome-induced humoral immune responses by non-ionic block polymer surfactants in Xid mice.

Non-ionic block polymers (NBPs) have proved to be potent adjuvants for the humoral immune response against liposomes haptenated with tripeptide-enlarged dinitrophenyl groups (hapten J). Since both reversed triblocks and normal octablocks displayed adjuvant activity, reversed octablocks, in which structural properties of both groups are combined, were also tested for their adjuvant activity. The latter compounds displayed very strong adjuvant activity for J-haptenated liposomes, not only in normal BALB/c but also in (CBA/N x BALB/c)F1 progeny. To test the applicability of NBPs as adjuvants in semi-synthetic vaccines, the capacity of NBPs to stimulate the immune response against liposomes haptenated with Streptococcus pneumoniae type 3 capsular polysaccharide-derived oligosaccharides was analysed. In these studies, again NBPs proved potent adjuvants, stimulating antibody production to a large extent. In male (CBA/N x BALB/c)F1 mice, which carry a X-chromosome-linked immunodeficiency (Xid), antibody levels were stimulated to the largest extent by a normal octablock. Stimulation of antibody titres, however, did not result in increased protection in these Xid mice.