Antibody synthesis stimulation by vitamin A in chickens

The effect of vitamin A on the immune response of chickens on primary and secondary immunization has been studied. It is demonstrated that the antibody content in chickens depends on the dose of vitamin A in the diet. In chickens fed a high dose of vitamin A in the diet the antibody content in the serum is 2 to 5 times as high as in chickens which have not been given vitamin A. An additional dose of vitamin A administered perorally any day following reimmunization increases the content of antibodies; the effect is most pronounced when vitamin A is given on the third day after reimmunization. In the period of maximal synthesis of antibodies (during the fourth day after reimmunization) labelled retinol is incorporated into the spleen of reimmunized chickens 13 times as actively as in the spleen of control chickens. In the in vitro experiments with antibody synthesis by spleen cells it has been demonstrated that addition of retinyl palmitate to the incubation medium enhances antibody synthesis during incubation. Addition of retinyl palmitate to the spleen cells of vitamin A-deficient chickens restores the synthesis up to the level observed in the control cells. The suggestion is discussed that the effect of vitamin A on the immune process is realized at the level of immunoglobulin synthesis.