Excretion of kidney brush border antigens as a quantitative indicator of tubular damage.

The excretion of antigens and enzymes derived from the brush border region was studied in patients with kidney diseases, after kidney transplantation, during administration of potential nephrotoxic drugs, before and after operations etc. The main portion of membrane constituents was excreted in the urine at an increased rate, compared to healthy persons, and was identical with glycoproteins artificially released from the brush border membrane surface. Antisera against brush border antigens, which had been isolated from urine by affinity chromatography, were used to localise the origin of urinary kidney tissue-proteins applying immunofluorescence microscopy.