MONOCLONAL-ANTIBODIES AGAINST RAT GLOMERULAR ANTIGENS - PRODUCTION AND SPECIFICITY

Abstract

To define the characteristics and target antigens (Ag) of nephrotoxic antibodies (Ab) and to analyze the factors that govern the evolution of Ab-mediated glomerular injury, monoclonal Ab were prepared against rat glomerular Ag. BALB/c mice were immunized with Lewis rat cortex or glomeruli, and their spleens were removed and fused with hypoxanthine-aminopterin-thymidine supplement-sensitive myelomas. Hybrids were selected from production of Ab against Lewis rat kidney by indirect immunofluorescence. More than 50 positive hybrids were selected and their tissue reactivity defined by indirect immunofluorescence and immunoelectron microscopy. Of these, 14 and presented here in detail. One of these monoclonal Ab, K9/4, recognizes a unique Ag present exclusively on the cell surface of rat glomerular visceral epithelial cells. Four Ab (K12/2, K17/4, K12/5 and K12/8) recognize sites within the glomerular basement membrane; K12/2 and K17/4 also bind to vascular basement membranes of the rat; K12/5 and K12/8 bind to glomerular basement membrane, tubular basement membranes and vascular and epithelial basement membranes in all tissues of the rat. Two hybridomas (K6/1 and K6/3) recognize determinant(s) present on cell surfaces of endothelial and epithelial cells as well as within the glomerular basement membrane. All of these previously mentioned Ab are species restricted (i.e., they bind only to rat tissue) and with the exception of K9/4, bind upon in vivo administration. Several others recognize ubiquitous Ag that are present on intracellular structures in every species tested. The tissue distribution of these Ag suggests that they are present in contractile or cytoskeletal elements and, as expected from their intracellular location, monoclonal Ab directed against these components do not bind upon in vivo administration. Future studies will be directed at defining the antigenic composition of the glomerular capillary wall and the relevance of such Ag in immune-mediated glomerular injury.