GLOMERULAR MACROPHAGE PHAGOCYTIC-ACTIVITY IN EXPERIMENTAL IMMUNE-COMPLEX NEPHRITIS

In rats with the proliferative immune complex glomerulonephritis of ch ronic serum sickness, kidney function deteriorates in three clearly di stinguishable and discrete stages: mild, moderate and severe. The macr ophage component of glomerular inflammation in each stage is also quan titatively and qualitatively distinct, with abnormal phenotypic marker s appearing in the moderate stage and increasing in the severe stage. To determine whether there were distinct functional differences among macrophages from the three stages, Fc gamma receptor-mediated phagocyt ic capacity was measured. The phagocytic capacity of glomerular macrop hages increased significantly in the moderate stage, then significantl y decreased, as rats progressed to severe chronic serum sickness. This decline in phagocytic function was not associated with a decrease in the expression of Fc gamma receptors on the glomerular macrophage cell surface. Furthermore, the phagocytic function of peritoneal macrophag es from rats with severe chronic serum sickness was not impaired. Whet her or not this attenuation of glomerular macrophage phagocytic capaci ty is the cause, or result, of renal disease progression remains uncle ar. It may indicate a potentially protective role for intraglomerular macrophages, and can serve as an additional functional marker of disea se progression.