The leukocyte subpopulations were analyzed within both the glomeruli and the interstitium in renal biopsies from 145 patients with various forms of glomerulonephritis. Cells were identified by monoclonal antibodies to leukocyte cell-surface antigens and immunoperoxidase labelling. Leukocytes, as defined by a monoclonal antibody to the leukocyte common antigen (PHM1), were present in normal, human renal tissue in both glomeruli (2.8 +/- 0.6 cells/glom. cross section) and interstitium (102 +/- 18 cells/mm2). Monocytes constituted the predominant infiltrating cell type in normal glomeruli (1.3 +/- 0.2) and T cells were rarely found (0.3: range 0 to 0.8), whereas both monocytes (34 +/- 10/mm2) and T lymphocytes (33 +/- 14/mm2) were found in the normal interstitium. In the non-proliferative forms of glomerulonephritis there was no significant increase in the number of glomerular inflammatory cells when compared with normal glomeruli. However, significantly increased numbers of T lymphocytes were seen in the interstitium of biopsies with minor non-specific changes (67 +/- 15/mm2), membranous nephropathy (134 +/- 30/mm2), focal glomerulosclerosis (207 +/- 53/mm2), and diabetic nephropathy (198 +/- 81/mm2). In the proliferative forms of glomerulonephritis only crescentic GN and post-infectious GN demonstrated significantly-increased glomerular monocytes and granulocytes. There was no significant increase in the number of glomerular T cells when compared with normal glomeruli. However, there was a significant increase in the number of interstitial T lymphocytes in all forms of proliferative glomerulonephritis when compared with the normal interstitial cell population.(ABSTRACT TRUNCATED AT 250 WORDS)