Abnormal podocyte CR-1 expression in glomerular diseases: association with glomerular cell proliferation and monocyte infiltration.

The expression of CR-1 complement receptors on glomerular epithelial cells, was studied in 77 renal biopsies from patients with (74) or without (3) glomerular diseases, employing an anti-CR-1 monoclonal antibody, and an indirect immunoperoxidase technique. Four patterns of CR-1 expression were recognised: normal (18); generally decreased (6); focal/segmental partial loss (44); and complete loss (9). Normal expression was detected in all three biopsies with non-glomerular diseases, and in glomerular diseases with normal glomeruli on light microscopy, but also in several glomerulonephritic biopsies (13), including diffuse proliferative lupus nephritis (1 of 7) and idiopathic membranous nephritis (5 of 14). However, the majority of biopsies from patients with glomerular diseases showed abnormal CR-1 expression (59 of 74), most evident in proliferative biopsies (43 of 49), with or without crescent formation (respectively, 18 of 20 and 25 of 29). Complete loss of CR-1 expression was almost restricted to crescentic biopsies (8 of 9). The abnormal CR-1 expression was unrelated to the presence of capillary immune deposits of Ig or C. More intraglomerular monocytes, assessed by monoclonal antibodies, were encountered in glomerulonephritic biopsies with partial CR-1 loss (median 6.2, P less than 0.05) or complete loss (median 14, P less than 0.03), than in biopsies with normal receptor expression (median 1.4). Thus, changes in glomerular CR-1 expression are frequently seen in many glomerular diseases and are associated with glomerular proliferative changes and monocyte infiltration, but not with the presence of capillary immune deposits.(ABSTRACT TRUNCATED AT 250 WORDS)