Neonatal-age treatment with vitamin A delays postweaning vitamin A deficiency and increases the antibody response to T-cell dependent antigens in young adult rats fed a vitamin A-deficient diet.

Vitamin A supplementation for infants and young children is recommended by WHO/UNICEF for countries with a high prevalence of vitamin A deficiency, and vitamin A is often administered at immunization contacts. Using a rat model, we tested whether supplementation with vitamin A or other retinoids at the time of neonatal immunization has prospective benefit in terms of preventing postweaning vitamin A deficiency and promoting antibody responses to T-cell dependent (TD) antigens administered at the neonatal stage and at the young adult stage. Rats were treated orally on postnatal d 6-8 with oil (placebo control), vitamin A, retinoic acid, or a combination of both (VARA) (n > or = 12/group), and immunized with tetanus toxoid (TT) on d 7. The primary anti-TT response was measured on d 21, after which weanling rats were fed the vitamin A-deficient diet until approximately 10 wk. At 8 wk, rats were immunized again with TT to determine the recall response, and with a novel TD antigen, keyhole limpet hemocyanin (KLH), to assess the adult primary response. None of the supplements affected the plasma titer of anti-TT immunoglobulin G (IgG) on d 21 (P = 0.25). However, neonatal-age supplementation with vitamin A or VARA at the young adult stage resulted in: >5 times higher anti-TT IgG recall response (P < 0.01); 5- and 9-times higher anti-KLH primary IgM and IgG responses, respectively (P < 0.05), and plasma retinol in the normal range (approximately 1.0 micromol/L vs. approximately 0.35 micromol/L in retinoic acid-treated and control groups, P < 0.0001). We conclude that early-life supplementation with vitamin A or VARA can prospectively benefit the primary and recall antibody responses to TD antigens administered at the young adult stage, which may involve the maintenance of normal plasma retinol levels.