Expression and release of intercellular adhesion molecule-1 in renal-cancer patients

We examined ICAM-1 expression in 37 freshly dissociated renal-cancer cell populations. Immunoperoxidase analysis revealed that 31 of the 37 renal tumors expressed ICAM-1 to various degrees; ICAM-1 expression was 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 value 40.8% ± 22), and the low expression of this molecule on the cell surface seemed to correlate with favorable clinical behavior. In 41 patients, the mean level of sIAM-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 metastatic patients (mean 631 ± 318 ng/ml). Eleven renal-cancer cell populations were cultured in order to examine the expression and release of ICAM-1. All of these cells were positive for ICAM-1 expression, which was 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 cellular expression. Five of the cell populations were treated for 48 hr with rIFN-γ; in these cells, both ICAM-1 expression and sIAM-1 levels increased, although sICAM-1 levels in the supernatants of the cell populations with constitutive high ICAM-1 expression remained very low.