Quantitation of intraglomerular mononuclear phagocytes in experimental glomerulonephritis in the rat using specific monoclonal antibodies.

Intraglomerular mononuclear phagocytes were quantitated, in normal Sprague-Dawley rats and in animals with diffuse proliferative glomerulonephritis, using recently described specific monoclonal antibodies (ED1, ED2, ED3) and a 4-layer immunoperoxidase technique. Results obtained with the immunoperoxidase technique were compared with estimates of glomerular mononuclear cellularity based upon glomerular histochemistry and glomerular cell culture. Normal animals (n = 12) had no significant glomerular mononuclear phagocyte population by immunoperoxidase [0.01 macrophages per glomerular cross section (MO/gcs)], histochemistry (+0.2 +/- 0.1 staining intensity) or glomerular cell culture [0.10 +/- 0.02 MO/glomerulus (MO/glom)]. Evolution of diffuse proliferative glomerulonephritis was associated with a progressive rise in glomerular mononuclear phagocyte infiltration using all three techniques. Immunoperoxidase staining (ED1) at the time of maximal macrophage infiltration of glomeruli revealed 6.21 +/- 1.78 MO/gcs (n = 12) using the ED1 macrophage marker. This correlated with histochemical (+3.8 +/- 0.2 staining intensity) and glomerular cell culture (17.6 +/- 4.5 MO/glom) estimates of the glomerular mononuclear phagocyte population. In addition, significant numbers of intraglomerular monocytes possessed the ED2 and ED3 macrophage differentiation antigens (0.82 +/- 0.41 and 0.24 +/- 0.15 MO/gcs respectively). Thus these specific monoclonal antibodies provide a reliable and readily reproducible means for the quantitation of intraglomerular mononuclear phagocytes. In addition, they provide evidence for intraglomerular macrophage differentiation in experimental glomerulonephritis in the rat.