Effect of malnutrition and BCG vaccination on macrophage activation in guinea pigs

Abstract

Host defense functions, particularly cell-mediated immunity, may be profoundly altered by malnutrition. Activated macrophages are required as effector cells in the final stages of a successful cell-mediated immune response against microbial pathogens. Macrophage activation was assessed by measuring the activity of superoxide dismutase (SOD) in peritoneal macrophages obtained from BCG-vaccinated and non-vaccinated guinea pigs maintained on purified diets containing 8% or 25% casein. Protein deficiency, as measured by reduced hemoglobin and serum albumin concentrations, was accompanied by significant reductions in delayed hypersensitivity to purified protein derivative (PPD) and impaired lymphocyte blastogenic responses in vitro to PPD and phytohemagglutinin. In contrast, macrophage SOD activity was inversely correlated with protein nutritional status, irrespective of vaccination. These results suggest that the thymus-dependent (T) lymphocyte subsets responsible for delayed hypersensitivity, blastogenesis and macrophage activation may be affected differently by protein deprivation. Alternatively, enhanced macrophage activity may not be the result of T cell function in this model.