Expression of indoleamine 2,3-dioxygenase (IDO) in epithelium of the endometrium and the cervix is not restricted to normal but also present in carcinomatous tissue. The enzyme was found in the majority of cases studied, pioneer cells at the invasion front of the tumors being especially strongly reactive in immunohistology. In addition, also cells in the peritumoral infiltrate of the stroma expressed IDO. Taken together, these findings together with previous data on the immunosuppressive impact of tryptophan depletion suggest IDO-induced suppression of antitumoral immune response in both adenocarcinoma and squamous cell carcinoma of endometrium and cervix. On the other hand, IDO as also known to inhibit tumor cell proliferation by tryptophan depletion.

A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cells from BALB/c mice immunised with human sperm cells. The antibody was determined to be an IgG1. The corresponding antigen is present on the whole surface of ejaculated human spermatozoa. It is not detectable on spermatozoa of other mammalian species (rabbit, cat, dog, sheep, boar, bull, horse). In human male genital organs, immunostaining with GZS-1 is observed on sperm cells in the epididymis and the ductus deferens together with the lining epithelium of those organs. No reactivity of sperm cells or germ cell precursors in the testis has been detected. Functional tests using the antibody show a strong inhibitory effect on human sperm in the hamster egg penetration assay. Furthermore, the GZS-1 antigen is detectable on the surface of human lymphocytes and monocytes by immunogold electron microscopy and FACS analysis. By Western blotting of human sperm and seminal plasma performed under reducing conditions immunostaining was detected at 21–25, 31, 51–54, and 62 kDa. The reaction with human lymphocytes shows one major band at 62 kDa and additional bands at 31 and 54 kDa. The results suggest that the monoclonal antibody GZS-1 may recognise an antigen which is secreted from the epithelial cells of the epididymis and binds to ejaculated spermatozoa as a sperm coating antigen. This component may be involved in the capacitation of the sperm and the acrosome reaction. Molecules that are expressed both on sperm and on immunocompetent cells may be relevant for the regulation of immunological processes or for the development of the related immunological tolerance of sperm in the female reproductive tract.