Serum ICAM-1 in renal cell cancer patients: Possible significance for presence of metastatic disease

Background Intercellular adhesion molecule-1 (ICAM-1) facilitates cell-to-cell adhesion through lymphocyte function associated antigen-1 (LFA-1). ICAM-1 also exists as a soluble form (sICAM-1) and the level of sICAM-1 is known to increase in the presence of malignant tumors. Previously, we reported frequent ICAM-1 expression in renal cell cancer (RCC). sICAM-1 may suppress antitumor immune reactions by blocking LFA-1 on lymphocytes. Methods Serum sICAM-1 and IL-6, possible RCC autocrine growth factors, were examined in 35 RCC patients before and after surgery. In situ expression of sICAM-1 in RCC tissue and the degree of macrophage and lymphocyte infiltration were evaluated semiquantitatively using immunohistochemistry techniques. Results Nine pre- and 12 postoperative patients had elevated sICAM-1 levels. RCC patients with elevated sICAM-1 levels revealed a high ICAM-1 expression and/or high degree of lymphocyte/macrophage infiltration. Elevation or persistence of high sICAM-1 levels after nephrectomy correlated with the presence of metastatic disease (P=0.02); sICAM-1 was elevated in 5 of the 7 (71%) patients with metastasis compared with 7 of the 28 (25%) without evidence of metastatic disease. In some patients, however, the sICAM-1 level fluctuated without regard to the presence or absence of tumor after operation. Elevated sICAM-1 levels were also associated with high IL-6 levels. Conclusion Elevated sICAM-1 levels in RCC patients are not necessarily produced by RCC cells. However, in some cases, elevated sICAM-1 levels may be useful in detecting metastatic disease and aid in the development of treatment strategies and/or postnephrectomy follow-up therapies.