Cell surface expression and serum levels of intercellular adhesion molecule-1 in renal cell carcinoma

Intercellular adhesion molecule-1 (ICAM-1) is the natural ligand of the T-lymphocyte adhesion molecule LFA-1 (lymphocyte-function-associated antigen-1). ICAM-1 is involed in target cell recognition by T-lymphocytes, LAK cells and natural killer cells. The molecule has also been detected on a variety of normal cells and on human tumors. Renal cell carcinoma (RCC) is one of the few tumors that respond to immunotherapy, but clinical results are generally disappointing. We therefore analyzed, by immunohistochemistry, the expression of ICAM-1 in pairs of normal kidneys, RCC, and RCC metastases. Moreover, serum ICAM-1 was determined in RCC patients and compared with surface expression of cell-bound ICAM-1. Strong glomerular expression of ICAM-1 was observed in all specimens of normal kidney examined. Proximal tubuli were weakly stained in the majority of specimens. Of the tumors, 80% stained positive for ICAM-1. Although ICAM-1 was detected on the majority of extrarenal tumor specimens examined, staining was generally weaker in the metastases. Patients without metastases at initial presentation more frequently expressed ICAM-1 in their primary tumors than did patients with metastases. Levels of serum ICAM-1 (sICAM-1) were significantly higher in RCC patients than in controls with non-malignant renal diseases. Patients with an unfavorable prognosis, e.g. with advanced tumor stage or metastasis at initial presentation, had higher levels of sICAM-1 than patients with low-grade and/or low-stage tumors. An inverse correlation was observed between expression of ICAM-1 in tumors and levels of sICAM-1. On the basis of our data we suggest that cell-bound or soluble ICAM-1 is correlated with tumor-host interaction in RCC.