The immune responses to diabetes in BB rats supplemented with vitamin A

A substantial amount of evidence suggests that in type I diabetes, vitamin A and zinc status could be of concern because of their impaired metabolic availability. Because both vitamin A and zinc play important roles in the regulation of immune function, the present study was undertaken to examine the immune responses to vitamin A and zinc supplements in diabetic-prone Bio-Breed rats (BBdp), and if the supplements increase the incidence of diabetes. Weanling BBdp rats were fed a NIH-07 diet supplemented with vitamin A either alone or in combination with zinc up to 120 days of age. A greater percentage of rats developing diabetes was found in rats that had supplements of vitamin A and zinc (67%) than those on the basal diet (55%) or with vitamin A supplementation alone (50%). The B cells and macrophages were all markedly increased, whereas CD(4)(+) and CD(8)(+) T cells were decreased at the onset of diabetes. However, this immune status was not changed by vitamin A and zinc supplements. The plasma vitamin A levels were significantly decreased in the presence of diabetes and the vitamin A status did not improve when the rats were given vitamin A and zinc supplements. The Natural Killer cell cytotoxicity on a per-cell basis was significantly decreased in the presence of diabetes, irrespective of supplements with vitamin A and zinc. Overall, results indicated that vitamin A and immune status are both affected by type I diabetes; these effects, however, are not responsive to supplemental intakes of vitamin A either alone or in combination with zinc.