Comparison of APF activity and epithelial growth factor levels in urine from Chinese, African-American, and white American patients with interstitial cystitis

Objectives. Interstitial cystitis (IC) is a chronic bladder disorder for which the etiology is unknown. We have previously shown that antiproliferative factor (APF), heparin-binding epidermal growth factor-like growth factor (HB-EGF), and epidermal growth factor (EGF) are sensitive and specific biomarkers for IC in white American patients. Because little is known about the epidemiology of this disorder, it is unclear whether these factors would also be useful biomarkers for IC in patients from different racial groups and/or geographic locations. Methods. Urine specimens were collected from Chinese, white American, and African-American women with IC and age and race-matched asymptomatic normal control women. APF activity was determined by ³H-thymidine incorporation into primary normal adult human bladder epithelial cells in vitro. The HB-EGF and EGF urine levels were determined by enzyme-linked immunosorbent assay. Results. The Chinese, African-American, and white American women with IC had significantly greater urine APF activity (P <0.000001, P = 0.0008, and P <0.000001, respectively), lower urine HB-EGF levels (P <0.000001, P = 0.02, and P <0.000001, respectively), and greater urine EGF levels (P <0.000001, P = 0.002, and P <0.000001, respectively), than their matched asymptomatic controls. Conclusions. These findings confirm the utility of APF, HB-EGF, and EGF as biomarkers for IC in patients from three different racial groups and two different countries.