Evaluation of urothelial Tamm-Horsfall protein and serum antibody as a potential diagnostic marker for interstitial cystitis

Demonstration of adherence of Tamm-Horsfall protein to bladder epithelium has been suggested as a potential diagnostic test for interstitial cystitis. Bladder specimens from 18 interstitial cystitis patients were evaluated by indirect immunoperoxidase techniques using a Tamm-Horsfall protein specific monoclonal antibody to determine the diagnostic value of the staining results. The study population consisted of 7 severely diseased patients who required cystectomy with urinary diversion and 11 other patients meeting National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases criteria for interstitial cystitis. We were unable to detect intraepithelial or surface-bound Tamm-Horsfall protein in any of the biopsy tissues. Human kidney tissue, similarly fixed and processed, consistently demonstrated Tamm- Horsfall protein staining of the kidney tubules. The monoclonal antibody also reacted on Western blots against urinary Tamm-Horsfall protein. Although antibody (α-Tamm-Horsfall protein) reactivity was measured by enzyme-linked immunosorbent assay in sera from interstitial cystitis patients, the titers did not differ statistically from those measured in sera from those without interstitial cystitis. Together, these results make it unlikely that immunohistochemical detection of Tamm-Horsfall protein will have diagnostic value in interstitial cystitis. Whether Tamm-Horsfall protein has a role in the pathogenic processes involved in this disease is not yet known. These findings do not eliminate the possibility that some interstitial cystitis patients will have abnormalities associated with the biochemical and physiological functions of Tamm-Horsfall protein.