Antisera to a Rabbit Urinary Tract Antigen also React with Human Bladder and Kidney Tissue

Abstract

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.

Urinary tract glycoprotein: distribution and antigenic specificity

“…The mAbs demonstrated high titers to rabbit GP1 purified from bladder mucosa and preferential binding to human GP1 preparations isolated from urine. This finding supports previous studies [6,22] suggesting that GP1 is phylogenetically conserved and establishing the application of these mAbs to the human system. The apparent increase in binding of the mAbs to GP1 preparations obtained from urine as opposed to tissue might be a result of differences in the purity and solubility of the extracts, i.e., identical amounts of antigen preparations do not contain the same quantities of the GP1 molecule.…”

“…The anti-GP1 mAbs bound to the mucin layer and epithelial cells of the bladder, the ureters, and the distal collecting tubules of the kidney, supporting the conclusions of previous studies that GP1 is produced throughout the urinary system but in a resticted manner [22]. In the kidneys, mAbs to GP1 reacted only with the distal collecting tubules.…”

“…Polyclonal antisera have proved to be a useful tool for analyzing the properties of GP1 as well as for observing its localization in the urinary tract. Previous studies have demonstrated the presence of GP1 in the lining of the urinary tract [6], its conservation among different species [22], and its reactivity with enteric bacteria (Escherichia coIi, Proteus mirabilis, Pseudomonas aeruginosa, Citrobacter diversus, Klebsiella pneumoniae and Enterococcus sp.) isolated from patients with urinary tract infections [20].…”

“…nally isolated from the bladder of New Zealand White (NZW) rabbits, GP1 or an antigenically similar molecule was found in rats, guinea pigs, hamsters, and humans, suggesting that GP1 is phylogenetically conserved [6,22]. The subunit size of GP1 has been estimated to be approximately 51 kDa in urine and is capable of aggregating to 500-600 kDa (unpublished data).…”

“…This material as the primary immunogen also produced antibodies reactive to 22 THP and host serum albumin [22]. Herein, we describe the successful production of monoclonal antibodies (mAbs) to GP1 that exhibit a specificity distinct from that of anti-THP and anti-URO-5 m A b s as measured by solidphase immunoassays and immunohistochemical procedures.…”