Using the technique of somatic cell fusion, we produced monoclonal antibodies to collagenase-digested human glomerular basement membrane (GBM). Fourteen monoclonal antibodies which reacted with normal human kidney in indirect immunofluorescence (IIF) studies were produced. An analysis of the binding patterns indicated that the antigens recognized could be divided into six broad groups. Monoclonal antibody B3-H10 (Group 1) reacted with only GBM in a fine granular pattern. A5-B12 and B5-C2 (Group 2) reacted with GBM and peritubular capillary in a linear pattern. B2-A12 (Group 3) reacted with only epithelial cells. Al-C9 and A4-E2 (Group 4) showed a mesangial pattern in glomerulus and a lineal pattern in tubular basement membrane (TBM), Bowman's capsule and peritubular capillary. A1-E1, A1-E11, A2-E6, A3-B6, A4-F8 and B5-H2 (Group 5) recognized determinants common to GBM, TBM, Bowman's capsule and/or peritubular capillary. A3-F1 and B5-E10 (Group 6) reacted with TBM and Bowman's capsule. The staining pattern of B3-H10 (Group 1) was characteristic because it was not linear, but finely granular along the GBM. The staining pattern of B2-A12 (Group 3) was also characteristic because only epithelial cells were stained, and processes of epithelial cells were observed as fine fibrils. To the best of our knowledge, these two types of monoclonal antibodies have not been reported previously.</p