Upregulation of major histocompatibility complex (MHC) antigen in nephritis associated with murine malaria infection.

The importance of immune complexes in the pathogenesis of malarial nephritis is well established. The expression was studied of major histocompatibility complex (MHC) class I and class II antigens and the infiltration of inflammatory cells, with their possible roles in cellular immune reactions in the pathogenesis of nephritis in a murine malaria model. Thirty-six kidney sections obtained on days 5, 8-10, 15, and 20 from C57BL/6J mice acutely infected with Plasmodium berghei and uninfected control mice were stained with specific antibodies for cellular immune markers by immunohistochemistry. From day 10 post-infection, markedly enhanced expression of both MHC class I and class II (Ia) antigens was observed in the kidneys. In the glomeruli, the expression was in the mesangium and along the capillaries. MHC class II was strongly expressed in the proximal tubules. Enhanced expression of MHC class I and class II was found in the endothelium of blood vessels, especially the peritubular capillaries. In addition, immune cells positive for CD4+ and CD8a+ markers, and class I and class II antigens were present around small arteries, or in focal areas of the interstitium. There were strong correlations between MHC class I expression in the glomeruli; MHC class II expression in the glomeruli/proximal tubules; and CD4+, CD8a+ infiltrates in the tubulointerstitium; with the severity of renal dysfunction (proteinuria). These findings indicate the importance of cellular immune reactions in the pathogenesis of acute murine malarial nephritis.