Effects of prenatal and postnatal exposure to vitamin A on the development of the murine immune system.

Vitamin A and its derivatives are known to enhance the immune system and affect embryogenesis. In this study, five daily subcutaneous injections of retinol palmitate (0.001 mg/kg body weight) were administered to eight female SW mice before mating. Six more weekly injections of retinol palmitate were given during pregnancy and lactation. Eight controls were similarly treated with saline. Four of the eight vitamin-A-treated females had litters, whereas seven of the eight saline-treated females had litters. Resultant litters did not differ in size or appearance. At 12 weeks of age, serum IgM and IgG1 levels were significantly higher in the progeny of vitamin-A-treated mothers before but not after immunization with a test antigen, sheep red blood cells (SRBC). This difference was not seen when other progeny were tested at the age of one year. Anti-SRBC titers did not differ in the two groups of progeny at the age of 12 weeks or one year. One-year-old progeny of vitamin-A-treated mothers weighed significantly more than did control progeny; significant enlargement of the heart, spleen, and kidneys was observed. However, organ-to-body-weight ratios did not differ significantly. In a separate experiment, adult female mice treated with varying doses of vitamin A (five daily doses of 0.0001, 0.0005, or 0.001 mg/kg body weight) showed a dose-dependent reduction of serum IgG1 and hematocrits, but no change in serum IgM levels or leukocyte counts. Resting untreated mice had IgM levels which were one-half those seen in saline-treated controls. These studies indicate that large doses of vitamin A can affect some aspects of the developing and mature murine immune system.