Sertoli cells, but not tumor cells, of seminoma in situ express ICAM-1.

Tumor and surrounding testicular tissue from six seminomas and one combined seminoma/embryonal carcinoma were examined for the expression of ICAM-1, VCAM-1 and ELAM-1. This was done by immunohistochemical staining of frozen samples using monoclonal antibodies and the avidin-biotin/ peroxidase or alkaline phosphatase staining method. ICAM-1 was expressed by Sertoli cells of intratubular germ cell neoplasia, but not by any of the cells in normal seminiferous epithelium, or by neoplastic germ cells whether invading or not. In addition inflammatory cells and endothelium expressed ICAM-1. VCAM-1, and also occasionally ELAM-1, was expressed only on endothelial cells in and outside the tumors. These results are discussed in relation to lymphocytic infiltration and immune surveillance of seminomas and T-cell tolerance to the antigens of the immunologically privileged seminiferous epithelium.