Distribution of blood group antigen A in normal and pathologic human kidneys.

We tested this distribution with an indirect immunofluorescent technique using purified rabbit anti-A antiserum on 21 whole normal kidneys (a group, N equal to 18; AB group, N equal to 1; O group, N equal to 2) and on 349 kidney biopsy samples (A group, N equal to 140; AB group, N equal to 14; O or B group, N equal to 195) representing a large spectrum of renal diseases. In normal kidneys from A and AB groups, the A antigen was detected in the whole vascular endothelium and in the convoluted distal tubules. In secretors, collecting tubules were brightly positive. Epithelial staining was more diffuse in the inner part than it was in the outer part of the medulla. The basement membrane of the inner collecting tubules was positive in frozen sections but not in paraffin sections. In pathologic kidneys, modifications were obvious: (1) The thickened basement membrane of atrophic convoluted distal tubules was brightly stained. (2) Endothelial staining allowed a precise appreciation of the glomerular and interstitial vasculature. (3) In proliferative changes such as arterial intimal proliferation, proliferative glomerulonephritis, and interstitial cell infiltration, endothelial cells do not proliferate. This routine staining technique of endothelial cells by anti-A antiserum provide information not obtainable with light microscopy.