Identification of specific glomerular cell types in culture by use of lectin and antibody binding

To characterize the outgrowth of cells from cultured rat glomeruli, we examined the cell morphology in relation to the expression of various antigenic determinants (factor VIII-related antigen, rat Thy 1.1, Heyman nephritogenic antigen, common leucocyte and Ia antigens) and lectin binding patterns. For this purpose, early (3–7 days) to late (4–5 weeks) glomerulus cultures, as well as subcultures of mesangial cells were used. In the early samples, the predominance of small round (type I) cells growing in a cobblestone pattern was noted. These cells failed to express specific binding for any of the antibodies or lectins tested. 5–10% of the outgrowing cells appeared single and morphologically of stellate shape (type II). These cells were reactive for Concanavalia ensiformis (ConA), Triticum vulgaris (WGA) and Ricinus communis (RCA I), and stained for rat Thy 1.1 antigen. Large round, single cells (type III), found mostly at the edges of the outgrowth bound only Bandeiraea simplicifolia (BSI-B4) and FVIII antibodies, a pattern consistent with endothelial cells. A fourth (type IV) cell type, elongated, with cells mostly found in bundles and growing on a layer consisting of other cells, was reactive for ConA, WGA, Limax flavus (LFA) and Maclura pomifera (MPA) lectins. In the late outgrowth (3–5 weeks after explant), the lectin and antibody binding patterns of each cell type remained essentially unchanged. However, considerable changes in the prevalence of the morphologic cell types were noted. Cells that had been subcultured to obtain pure ‘mesangial’ cells, exhibited the same morphology as the type II cells and expressed identical staining patterns with all probes used. The binding of lectins was likewise confirmed by staining frozen sections of rat kidneys.