Immunologic Competence of Hemodialysis Patients following Withdrawal of Vitamin C Supplement

Abstract

Twelve stable nondiabetic patients on chronic hemodialysis were studied for their immunobiologic competence while receiving vitamin C supplement and 1–2 months following its withdrawal. These subjects, on prescribed diets, were checked for their food intake at the beginning of the study and at 1-month intervals thereafter. Immunological parameters tested were: (1) plasma vitamin C levels; (2) number of mononuclear cells isolated from blood and their vitamin C contents; (3) lymphocyte blastogenic response to mitogens; (4) leukocyte metabolic functions in presence of endotoxin by nitroblue tetrazolium reduction test, and (5) delayed hypersensitivity to skin-testing antigens, e.g. Candida and mumps antigens and purified protein derivative. Patients on vitamin C had significantly higher plasma ascorbic acid levels compared to normal healthy subjects. These decreased to low normal levels 1 month following withdrawal of the supplement and stayed comparable thereafter, up to 12 months of the study period. Ascorbic acid contents in the isolated mononuclear cells remained unchanged in patients on or off vitamin C. The number of blood mononuclear cells isolated and mitogenic responses to concanavalin A and phytohemagglutinin did not change following withdrawal of vitamin C supplement. All patients had positive delayed hypersensitivity to Candida, 60% to mumps and all were unresponsive to purified protein derivative. Leukocyte metabolic functions by nitroblue tetrazolium reduction test were higher in patients on vitamin C than when off, but this was not statistically significant. Vitamin C supplement is not necessary in hemodialysis patients when they are on an adequate diet.