Expression of CD30 in Testis and Epididymis of Adult Mice

CD30 antigen is a member of the tumor necrosis factor (TNF) receptor superfamily (Smith et al., 1990; Durkop et al., 1992), which was originally identified on ReedSternberg cells of Hodgkin’s diseases (Schwab et al., 1982). CD30 was subsequently revealed to be expressed also in different non-Hodgkin’s lymphomas (NHLs), as well as in several virally transformed Tand B-cell lines (Herbst et al., 1993; Gruss and Dower, 1995), and normal CD45RO T cells after activation by a variety of T-cell stimuli (Ellis et al., 1993). Further studies have described that CD30 expressed on normal T and B lymphocytes following activation is involved in cell activation, differentiation and death (Gruss et al., 1994a; Gruss et al., 1994b; Telford et al., 1997; Opat and Gaston, 2000). Therefore, CD30 has been extensively studied for clinical application as a specific marker for diagnosis (Piris et al., 1990; Hodges et al., 1991; Paulli et al., 1995) or a target molecule for treatment (Barth et al., 2000; Levi et al., 2001; Willers et al., 2003) of lymphomas. CD30 has been also proposed as a type 2 helper T (Th2) cell marker (Romagnani et al., 1995; Annunziato et al., 1998) despite several debates (Bengtsson et al., 1995; Hamann et al., 1996). In consideration that polarized Th1/Th2 response is causally related with pathogenesis of diseases (Romagnani, 1996; Romagnani et al., 1997), identification and functional control of type 2 helper T (Th2) cells using CD30 antigen may provide important clues for successful therapies of those related diseases (Romagnani, 1995; Romagnani et al., 1995; D’Elios et al., 1997). CD30 outside lymphatic system has been rarely found. To our knowledge, CD30 expressed by normal nonhematopoietic cells was documented solely on decidual endometrial stromal cells (Papadopoulos et al., 2001). Another types of non-hematopoietic cells expressing CD30 are several germ cell tumors including embryonal carcinomas (Pallesen and Hamilton-Dutoit, 1988; Latza et al., 1995), seminoma or mixed germ cell tumor (Pallesen and Hamilton-Dutoit, 1988), and mesenchymal tumors (Mechtersheimer and Moller, 1990). Furthermore, CD30 expression was down-regulated during stem cell differentiation of in vitro cultured embryonal carcinoma cells (Pera et al., 1998). All of these reports showing CD30 distribution in reproductive system raise a hypothesis that CD30 may play a role in germ cell differentiation. However, it remains unknown whether CD30 is expressed in developing germ cells or other somatic cells in reproductive system. Based on the fact that germ-cell tumors are the most common malignant neoplasms of the testis, we investigated a possibility of CD30 expression during spermatogenesis. Spermatogenesis has been studied most extensively in the mammalian testis (Eddy and O’Brien, 1994; Fawcett, 2001; Jung et al., 2001). Mammalian spermatozoa are produced in coiled tubes called seminiferous tubules of the testes. These seminiferous tubules consist of two types of somatic cells: the myoid or smooth muscle-like cells and the sertoli cells, and five types of germ cells: