Impaired biliary secretion of immunoglobulin A in vitamin A-deficient rats.

The effect of vitamin A deficiency on biliary secretion of IgA was investigated. Rats used in this study were rendered vitamin A deficient following withdrawal of retinoic acid from the diet of retinoate-cycled animals. This procedure allows a precise control of both the onset of deficiency and dietary protein-energy input. Defective synthesis and transport of IgA antibodies into the bile was evident when vitamin A-deficient rats (A-) were immunized by injections of either Brucella abortus or sheep red blood cells directly into the Peyer's patches. Antibody titers in the bile of A- animals were significantly lower than those of A+ controls (P less than 0.01). These A- rats also had significantly lower levels of total IgA in the bile compared with A+ controls (P less than 0.05). Moreover, the transport of labeled rat IgA injected intravenously was adversely affected in these animals. These results, together with our previous report on the impaired intestinal antibody in A- rats, clearly indicate that vitamin A deficiency interferes with the transport of IgA antibodies into the bile of these animals.