Blood group-related antigens in human germ cell tumors

With the use of immunohistochemical techniques, seven mouse monoclonal antibodies and the lectin from Ulex europaeus, detecting blood group antigens of the ABH and Lewis systems, have been used to define the distribution of these antigenic structures in germ cell tumors. The reagents used recognize the following blood group antigens: A, B, H, Lewisa, Lewisb, X (Lewisx), Y (Lewisy), and type I precursor antigen. Tumors from 29 patients were studied. Tumors studied consisted of pure embryonal carcinoma for eight patients, pure yolk sac tumor for two patients, embryonal carcinoma plus yolk sac tumor in one patient, and yolk sac tumor plus seminoma in one patient. Also studied were nine classic seminomas and a group of six patients with tumors classified as seminomas that exhibited atypical histological features. One patient had an anaplastic carcinoma arising from the mediastinum which could not be conclusively identified as a germ cell tumor morphologically and was analyzed separately. All embryonal carcinomas and yolk sac tumors exhibited strong positivity for type I precursor structure as detected by the K-21 monoclonal antibody. In marked contrast, there was non staining in classic seminomas but heterogeneous staining in five of six atypical seminomas. The majority of embryonal carcinomas and all yolk sac tumors studied demonstrated strong positivity for blood group antigen H. For seminoma, however, only one of the atypical cases and two of the classic cases (occasional cells) stained for H. Focal expression of the Y antigen was identified in 5 of 17 seminomas and in the majority of embryonal carcinomas and yolk sac tumors. Two yolk sac tumors and two classic seminomas expressed blood group X. The remaining blood group antigens were not expressed by seminomas while they were variably expressed by embryonal carcinoma and yolk sac tumors. These data suggest that K-21 and blood group antigen H may be distinguishing markers of nonseminomatous germ cell tumor versus seminoma. If so, it is possible that the heterogeneous expression of blood group substances in seminomas with atypical histologies is an indication of differentiation towards nonseminomatous germ cell tumor.