Impaired Biliary Secretion of Immunoglobulin A in Vitamin A-Deficient Rats

Abstract

Abstract

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 < 0.01). These A^- rats also had significantly lower levels of total IgA in the bile compared with A⁺ controls (P < 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.