Antisera to a rabbit urinary tract antigen also react with human bladder and kidney tissue.

The mucin layer covering the bladder transitional cell mucosa appears to function as a primary defense mechanism against bacterial infection. We have previously prepared a glycoprotein fraction (GP1) from the urinary bladder mucosa of NZW rabbits and raised murine antisera against it. These antisera react with bladder, ureter and kidney tissue from rabbits, rats, guinea pigs, and hamsters. We now show that a similar substance occurs in human kidneys and bladder. In order to remove antibodies reactive with the Tamm-Horsfall protein (THP), the antisera were initially absorbed with an immunoadsorbent composed of purified human THP covalently bound to Sepharose CL-4B gel. Using an enzyme linked immunosorbent assay (ELISA) it could be shown that the absorbed antisera did not react with THP but retained a high titer in binding to GP1. Immunohistochemical procedures involving avidin-biotin-immunoperoxidase staining demonstrated that the absorbed anti-GP1 reacted well with six human urinary bladder biopsy specimens and two kidney autopsy specimens while normal murine sera showed little or no binding. Although this reactivity was not as strong as that found with homologous tissue (rabbit) these studies suggest that GP1, an antigen common to several animal species, is also related to a human urinary tract component.