IDENTIFICATION OF A RENAL PROXIMAL TUBULAR EPITHELIAL ANTIGEN COEXPRESSED ON LEUKOCYTES

Renal tubular epithelial cells (TEC) and leukocytes express distinct c ell adhesion molecules and integrins in common. To identify additional proximal TEC molecules that are coexpressed on leukocytes, we have ge nerated a panel of monoclonal antibodies (mAb) by immunization of rats with a mouse T cell line. One of these mAb (I-72) recognizes a 210-kD antigen on cultured TEC. The staining pattern in several cell lines a llowed exclusion of known TEC surface molecules as being the antigens recognized by the I-72 mAb. Immunofluorescence staining of mouse kidne y with the I-72 mAb demonstrated prominent expression on the apical bu t not the basolateral side of proximal tubules, predominantly in the S 1 segment. I-72 was also expressed in the loop of Henle, the collectin g duct, and on endothelial cells of intrarenal vessels. We have thus g enerated st mAb which identifies an unusual. renal proximal tubular br ush border molecule that is coexpressed on T cells. Molecular structur e and the function of I-72 need to be defined in further studies.