Deduction from Wilms' tumour that glomerular podocytes produce the basement membrane material bearing Goodpasture determinants.

Using an indirect immunoperoxidase technique, we tested frozen specimens from one Wilms' tumour composed of numerous glomeruloid bodies devoid of blood vessels, with monoclonal antibodies directed against vimentin, cytokeratin, CALLA/CD10, CD24, CR1/CD35, endothelium factor VIII, class I and II MHC molecules, laminin, fibronectin, and non-collagenic domain NC1 of type IV collagen. Two reagents against Goodpasture determinants were used: P1 monoclonal antibody and serum IgG (GP antibodies) from a biopsy-proven Goodpasture patient. Glomeruloid bodies comprised two cell types: a peripheral layer of parietal epithelial cells (cytokeratin and CD24-positive) and central cell clumps of podocytes (vimentin and CALLA-positive). The basal lamina surrounding the glomeruloid bodies contained laminin and NC1 domain of type IV collagen, while that present between the podocytes reacted strongly with laminin, and P1 and GP antibodies. Endothelium factor VIII was not detected within the glomeruloid bodies and CR1 molecules bound to the basement membrane material within them. These data favour the hypothesis that podocytes produce the basement membrane material which bears Goodpasture determinants recently identified as a novel chain, named the alpha 3 chain, of type IV collagen.