We phenotyped with monoclonal antibodies (MAb) the cellular infiltrates in kidneys of patients with rapidly progressive glomerulonephritis (RPGN) responsive (R) or nonresponsive (NR) to pulse methylprednisolone therapy (PM)-eight anti-GBM, six no immune deposits, three immune complex, two vasculitis, and one proliferative GN. There were glomerular, periglomerular, crescentic, and interstitial T and T-cell subsets. Few interstitial and no glomerular B and NK cells were observed. TH cells were much more common than TS. Phenotypes were quantitatively evaluated in 221 nephritic and 32 control glomeruli. T and/or TH cells were positively correlated with M phi, r = 0.30 to 0.74, P less than 0.05 to 0.0005. Although differences in phenotypes were observed, these differences were insufficient to distinguish between subtypes. Analysis of R and NR revealed no relationship to percent crescents, entry serum creatinine, oliguria, or need for dialysis. NR was related to presence of anti-GBM disease, P = 0.001, as was ability to stop dialysis, 0 of 7 GBM versus 9 of 10 other, P less than 0.001. Mild infiltrates of lymphocytes and M phi correlated with R, P less than or equal to 0.02. R had fewer numbers of TH and M phi in glomeruli, P = 0.0001, in crescents, P less than 0.02, and total TH and M phi compared to NR, P less than 0.001. Crescentic and total TH/S ratios were lower in NR than R, P less than 0.05. These findings demonstrate that components of the cell-mediated immune (CMI) system are present by MAb analysis, that subtypes cannot be differentiated by CMI constitution, and R to PM is related to intensity and composition of CMI involvement. Independence of the CMI system relative to anti-GBM disease remains to be clarified.