SERTOLI CELLS, BUT NOT TUMOR-CELLS, OF SEMINOMA IN-SITU EXPRESS ICAM-1

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