Nutritional factors and autoimmunity. IV. Dietary vitamin A deprivation induces a selective increase in IgM autoantibodies and hypergammaglobulinemia in New Zealand Black mice

Abstract

The role of nutrition in modulating autoantibody expression in murine lupus has become well documented. One such nutritional factor, zinc deficiency, has received significant attention because of the well-known effects of zinc on the immune function of genetically normal animals. Moreover zinc-deficient diets retard autoantibody production in NZB, NZB/W, and MRL/1 mice; such deprivation also enhances survival in all three strains. Because zinc nutriture influences vitamin A metabolism, it has been postulated that the immunologic effects of zinc deficiency are mediated in part by the reduction of vitamin A levels seen in zinc deprivation. To explore this possibility we studied the influence of vitamin A deficiency, in zinc well-nourished mice, on autoantibody production in NZB mice. Groups of NZB mice, beginning at 6 mo of age, were fed a vitamin A-deficient diet or a control diet ad libitum or pair-fed to the deficient group. The diet contained casein as the protein source and contained adequate levels of trace elements and vitamins. Despite our hypothesis that the reduction of autoantibodies in zinc-deficient NZB mice might be mediated by secondary vitamin A deficiency, we found that vitamin A-deficient animals manifested more severe hypergammaglobulinemia and an earlier onset of both NTA and IgM anti-erythrocyte autoantibodies than did vitamin A-sufficient mice. These results illustrate the importance of rigorous studies of select nutritional parameters and warn of the possibility of clinical harm in feeding inappropriate diets to patients with systemic lupus erythematosis.