The antibody response of vitamin a-deficient rats to pneumococcal polysaccharide is enhanced through coimmunization with lipopolysaccharide

Although the antibody response of vitamin A-deficient rats immunized with pneumococcal polysaccharide (SSS-III) was barely detectable, coimmunization with SSS-III plus 2 or 20 μg of Pseudomonas aeruginosa lipopolysaccharide (LPS) resulted in an anti-SSS-Ill response that was equal to or greater than that of vitamin A-sufficient rats immunized only with SSS-III, Doses of 2 and 20 μg of LPS, but not 0.1 and 0.5 μg, produced significant adjuvanticity, and LPS functioned as an adjuvant when given concomitantly with SSS-Ill (day 0) or up to 3 days later. Thus, vitamin A deficiency per se does not preclude the anti-SSS-Ill response, and LPS or factors released in response to LPS, even after initiation of the response to SSS-III, may substantially enhance antibody production to this thymus-independent, type 2 antigen.