Influence of dietary pyridoxine on selected immune capacities of rat dams and pups.

The influence of dietary pyridoxine on passive antibody transfer from dams to pups and on active humoral antibody formation by the pups was studied. Rats were fed diets containing 20.0, 0.6, 0.45, or 0.3 mg pyridoxine-HCl/kg during gestation and 20.0, 0.4, 0.3, or 0.2 mg/kg during lactation (diets A, B, C, and D). Diets B, C, and D contained 100, 75, and 50% of the NRC requirement for pyridoxine during gestation and lactation. After pups in groups B, C, and D developed signs of pyridoxine deficiency, all dams were fed diet A on days 9 to 21 of lactation. On day 9 vitamin B-6 levels were lower in spleens and thymuses of pups and in milk in groups B, C, and D. However, IgG in sera of dams and pups and in milk indicated that passive antibody transfer was similar for all groups. After weaning, pups in groups A, B, C, and D were fed diets containing 20.0, 0.4, 0.2, and 0 mg vitamin B-6/kg, respectively. On day 35 vitamin B-6 levels were lower in spleens and thymuses of pups fed inadequate pyridoxine (groups B, C, and D). These pups had fewer spleen cells and splenic antibody-forming cells (AFC) and lower levels of humoral antibody. The reduction in spleen cells and splenic AFC resulted in part from lower food intake but was intensified by pyridoxine deprivation.