Glomerular involvement in human kala-azar. A light, immunofluorescent, and electron microscopic study based on kidney biopsies.

Glomerular involvement characterized by mesangial cell proliferation with fibrillar thickening of the axial region and deposits of immune complexes is reported in three human cases of kala-azar. IgG was seen in all 3 and Igm in 2 patients. Complement (C3) was detected in the glomeruli in all cases and fibrinogen in the only case in which it was tested for. The deposits appeared mainly along the mesangium and their staining was particularly strong for complement and IgG. Electron microscopy detected granular electron dense deposits mainly close to mesangial cells. In one case clumps made us of electron dense lamellae were seen in the glomerular basal membrane interpreted as evidence of focal membranolysis. No granulocytes were seen in the glomeruli. Attempts to demonstrate antigen were unsuccessful. The pattern of the lesion resembles that described in the kidney of human cases of hepatosplenic schistosomiasis, and the distribution of the deposits suggests that relatively large, poorly soluble complexes formed either in the presence of excess antigen or, under certain circumstances, in the presence of excess antibody, are trapped in the glomerular capillaries. The aggregates are partially shunted to the mesangial cells, which enlarge and proliferate.