EXPRESSION AND RELEASE OF INTERCELLULAR-ADHESION MOLECULE-1 IN RENAL-CANCER PATIENTS

We examined ICAM-1 expression in 37 freshly dissociated renal-cancer c ell populations. Immunoperoxidase analysis revealed that 31 of the 37 renal tumors expressed ICAM-1 to various degrees; ICAM-1 expression wa s significantly lower in tumor cells obtained from patients remaining tumor-free after a median follow-up of 60 months (mean value 24.4% +/- 21) than in tumor cells obtained from the relapsed patients (mean val ue 40.8% +/- 22), and the low expression of this molecule on the cell surface seemed to correlate with favorable clinical behavior. In 41 pa tients, the mean level of sICAM-1 was 551 +/- 260 ng/ml, significantly higher than normal. However, sICAM-1 levels were significantly lower in the 20 tumor-free (mean 467 +/- 158 ng/ml) than in the 21 metastati c patients (mean 631 +/- 318 ng/ml). Eleven renal-cancer cell populati ons were cultured in order to examine the expression and release of IC AM-1. All of these cells were positive for ICAM-1 expression, which wa s elevated in 6 cases (>50%) and low in the remaining 5 cases (18 - 35 %). However, only the 5 cell populations expressing low levels of ICAM -1 released this molecule, showing an inverse correlation with cellula r expression. Five of the cell populations were treated for 48 hr with rIFN-gamma; in these cells, both ICAM-1 expression and sICAM-1 levels increased, although sICAM-1 levels in the supernatants of the cell po pulations with constitutive high ICAM-1 expression remained very low. (C) 1995 Wiley-Liss, Inc.