Takao Negoro

Trophoblast-Derived Immunoregulatory Factor: Demonstration of the Biological Function and the Physicochemical Characteristics of the Factor Derived From Choriocarcinoma Cell Lines

ABSTRACT: An immunosuppressive factor released by choriocarcinoma cell lines was analyzed in the present study. It inhibited the proliferative responses of human T cells stimulated by lectins or alloantigens. It also blocked the generation of alloreactive cytotoxic T cells. The suppressive activity of the factor was detected in the responses of the T cells costimulated with 1 nM 12‐0‐tetradecanoyl phorbol 13‐acetate and 1 μM A23187, suggesting the possibility that the factor acted on the intracellular signal transduction in T cells rather than interfering with early events such as T cell receptor signal transduction through cell membranes. Moreover, the factor acted directly on T cell proliferation pathways without activation of suppressor cells but did not act on T cell activation pathways. Taken together, all these findings expanded our previous reports on a factor released by normal trophoblasts, indicating the possible identity of the two factors. The physico‐chemical properties of the choriocarcinoma‐derived factor were examined, and the biological significance of the factor during pregnancy was discussed in this paper.

Zygosity determination of multiple pregnancy by deoxyribonucleic acid fingerprints

We used a new method of deoxyribonucleic acid analysis to determine zygosity in multiple pregnancies. This method uses a minisatellite core probe, requires only a small amount of deoxyribonucleic acid, and detects the restriction fragment length polymorphisms that are a result of allelic differences in the number of tandem repeats that contain the core sequence. Southern blot hybridization showed an individual-specific deoxyribonucleic acid fingerprint and each polymorphic band in the sibling could be identified within one (but not both) of the parents. Identical deoxyribonucleic acid fingerprints among the siblings of multiple pregnancy indicate they must be monozygotic. This method is sufficiently reliable and rapid so the determination of zygosity in multiple pregnancy can be made the same day the fetal deoxyribonucleic acid is made available.

Analysis of site of action of a choriocarcinoma-derived immunoregulatory factor on IL-2-mediated T cell responses

We have investigated the functional ability of a choriocarcinoma-cell-derived factor to block human T cell responses and the factors immunoregulatory site of action on the T cell signal transduction pathway. The factor completely suppressed human T cell responses activated by phorbol ester and calcium ionophore, reagents which strongly stimulate IL-2-mediated T cell responses. It failed to inhibit CD 25 expression and IL-2 production by T cell blasts in the T cell activation phase, but completely blocked recombinant IL-2-induced proliferation of T cell blasts in the T cell proliferation phase. Absorption experiments with the factor and Con A-induced T cell blasts as well as [125I]IL-2 binding experiments with T cell blasts revealed that the factor acted on the physiological events occurring after IL-2-mediated stimulation of IL-2 receptor complexes, demonstrating no interaction of the factor with either IL-2 molecules or IL-2 receptor complexes. Moreover, it suppressed murine IL-2 dependent T cell line proliferation, suggesting the presence of common pathways in human and murine T cell proliferation. The biological and immunological significance of the factor during pregnancy and in the immunosuppressed tumor-bearing hosts are discussed.

Impaired Susceptibility of Human Trophoblast to MHC Nonrestricted Killer Cells: Implication in the Maternal-Fetal Relationship

ABSTRACT: Mammalian pregnancy has frequently been termed “Natures allograft,” and there is developing evidence that the placental trophoblast cells in their key position at the maternal fetal interface are responsible for escape mechanisms to the maternal immune system. In this paper, we show impaired susceptibility of human trophoblastic tumor cells to major histocompatibility complex (MHC) nonrestricted cytotoxicity systems such as natural killer (NK) cells and lymphokine‐activated killer (LAK) cells. LAK cells were induced by the culture of peripheral blood mononuclear lymphocytes (PBL) in recombinant interleukin‐2 (rIL‐2). Among 21 cultured cell lines derived from various tissues and organs tested, five choriocarcinoma‐derived cell lines gave decreased levels of LAK lysis. Cold‐target inhibition study and trinitrophenyl (TNP) modification experiment clearly indicated that the impaired sensitivity of trophoblast cells to LAK lysis is due to the decrease of a common target molecule recognized by LAK effector cells. It is suggested that the impaired susceptibility of trophoblast to MHC nonrestricted killer cells should be functional for the survival of the semiallogeneic fetus.

Clinical evaluation of the enzyme-linked immunosorbent assay (ELISA) kit for antisperm antibodies

A commercially available enzyme-linked immunosorbent assay (ELISA) kit for the detection of antisperm antibodies in serum was compared with standard sperm immobilization test (SIT) with the use of sera from 83 infertile women and 29 control individuals. For the ELISA, 24% of the infertile patients and 10% of the controls showed positive results, whereas 15% of the patients and none of the control were positive in the SIT. Parallel tests carried out on the same sera indicated that these methods detect a different, though often overlapping, spectrum of antibody activity. The presence and number of motile sperm in cervical mucus during postcoital tests were found to be related to the results of the SIT. On the other hand, the ELISA did not appear to be related to the quality of postcoital tests. These data indicate that care must be employed to interpret the results of this ELISA kit for the detection of antisperm antibodies.

QUANTITATIVE ESTIMATION OF ALLOANTISERA AGAINST MOUSE HISTOCOMPATIBILITY ANTIGENS ON MOTILITY OF SPERMATOZOA

Publisher Summary This chapter presents quantitative estimation of alloantisera against mouse histocompatibility antigens on motility of spermatozoa. In an earlier study, 6.5% of the sera from sterile women had antisperm antibodies, which were detected by sperm immobilization test; however, the control sera from pregnant women and unmarried women showed negative results. The human major histocompatibility antigens (HLA) are located on all the nucleated cells, including spermatozoa. If female possesses the antibodies against male HLA antigens, these antibodies can have the cytotoxic effect on spermatozoa and make the female sterile. In a study described in the chapter, alloantisera against mouse histocompatibility antigens were prepared in inbred strain mice. The antibodies against sperm specific antigens, completely immobilized the mouse spermatozoa under the existence of complement. The antisperm antibodies immobilize the syngeneic spermatozoa and also the allogeneic ones. The smaller amount of histocompatibility antigens on mouse spermatozoa can be one of the reasons why anti H-2 antibodies have no cytotoxic effect on spermatozoa.