Sertoli cells of intratubular germ cell neoplasia express β2 microglobulin

The cells in intratubular germ cell neoplasia in the vicinity of 38 germ cell tumors of the testis, including 20 pure seminomas, were studied for the expression of β 2 -microglobulin (β 2 m), the constant component of all HLA class I molecules. Immunohistochemistry using antibodies towards β 2 m, vimentin, placental alkaline phosphatase, and ferritin was employed. Whereas the intratubular cells in normal testis are β 2 m negative, β 2 m positive cells were identified in intratubular germ cell neoplasia tubules in 55 per cent of all tumors and in 60 per cent of the seminomas. The tubules with β 2 m positive cells were located in areas with invasive tumor or in the vicinity of such areas. The β 2 m positive cells were identified as Sertoli cells by morphology and by their staining with anti-vimentin. Neoplastic germ cells, identified by morphology and staining with anti-placental alkaline phosphatase and anti-ferritin were β 2 -microglobulin negative. The most intensely β 2 m-stained Sertoli cells were found in tubules with high concentrations of neoplastic germ cells. Intensely stained Sertoli cells were also found in 'Sertoli cell only' tubules inside invasive tumors and in areas without lymphocytic infiltration. The cells in adjacent normal tubules were β 2 m negative.