CONTRIBUTION OF MONONUCLEAR LEUKOCYTES TO THE PROGRESSION OF EXPERIMENTAL FOCAL GLOMERULAR SCLEROSIS

Uninephrectomized Sprague-Dawley rats repeatedly administered with aminonucleoside of puromycin and protamine sulfate developed progressive focal glomerular sclerosis (FGS). The contribution to disease progression of both glomerular and interstitial infiltrating leucocytes was studied throughout the disease evolution. Leucocyte subsets were quantitated with an immunoperoxidase technique using monoclonal antibodies for rat leucocyte surface antigens: OX1 (total leucocytes) OX6 (Ia positive cells), OX8 (suppressor/cytotoxic T cells), OX19 (total T cells), OX22 (B cells and subsets of T cells), and ED1 (macrophage/monocytes). In the glomeruli, macrophages and Ia positive cells were significantly increased when sclerotic lesions appeared, but T lymphocytes and subsets of T lymphocytes were not found. However, in the interstitium, all leucocytes were identified and increased in number throughout the disease evolution. Early in the disease, monocytes and lymphocytes were both present in large numbers, but at the end stage of the process, the predominant infiltrating leucocytes were CD4(+ve) T cells. In FGS rats treated throughout the disease with oral prednisolone (begun after disease induction), renal function was significantly better than in the untreated group, whereas the sclerosis and leucocyte accumulation in the glomeruli were unchanged. However, prednisolone treatment resulted in significantly fewer interstitial leucocytes and especially reduced the numbers of CD4(+ve) cells. These results suggest that the glomerular sclerotic lesions are related to the participation of macrophages independent of T cells, and that immune mechanisms mediated by T cells in the interstitium have an important role in the progression of this disease to end-stage renal failure. Such findings could infer that disease progression in glomerulonephritis, whether initiated by immune mechanisms or not, may be related to an interstitial immune inflammatory process mediated by lymphocytes and macrophages.