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Biomedical subjects

F Saji

Publications and source records attributed to F Saji.

At least 127 records · Page 7Linked to original sources
PubMed1990

HLA expression on human ejaculated sperm.

The expression of human leukocyte antigen (HLA) on human ejaculated sperm has been investigated by using cellular binding radioimmunoassay (CB-RIA) with sperm samples purified by Percoll discontinuous gradient and monoclonal antibodies specific to the frame work of HLA molecules. The results in packed sperm obtained from ten healthy males indicated that HLA class II and its subclasses, DP, DQ, and DR, were expressed at a low level on human ejaculated sperm, while HLA class I was not detected. Furthermore, we could not detect the individual variation of HLA expression on ejaculated sperm in the cases of twenty healthy males. K562, which is B lymphoid cell line and lacks HLA class I molecules, showed detectable amounts of HLA class I molecules after exposure to interferon gamma (IFN-gamma) and/or tumor necrosis factor alpha (TNF-alpha). However, the treatment of sperm with IFN-gamma and/or TNF-alpha had no effect on the expression of HLA class I and class II molecules.

Antibodies, Monoclonal↗
PubMed1990

Gene expression of macrophage colony-stimulating factor and its receptor in human placenta and decidua.

Macrophage colony-stimulating factor (M-CSF) induces proliferation of monocyte/macrophage progenitor cells and can also activate some functions of mature cells including fetally derived placental cells. To study the role of M-CSF in the pregnant female reproductive tract, the expression of M-CSF mRNA and its receptor, c-fms proto-oncogene, in human placenta and decidua was identified. M-CSF and c-fms mRNAs, 4.7Kb and 3.9Kb respectively, were detected by Northern blotting in the early stage placenta and subsequently increased during pregnancy. These mRNAs were not detected in the nonpregnant endometrium but were strongly induced in maternal decidua with the same mRNA size as in the placenta. Northern blot hybridization on the endometrium of a pseudopregnant uterus revealed that the expression of endometrial M-CSF and c-fms mRNAs is regulated by synergistic action of female sex steroid hormones. These findings indicate that, in an autocrine and/or paracrine manner, M-CSF is deeply involved in the local proliferation and differentiation of cells at the materno-fetal interface, and support the placental immunotrophism hypothesis.

Blotting, Northern↗
PubMed1990

Trophoblast-derived interleukin-6 (IL-6) regulates human chorionic gonadotropin release through IL-6 receptor on human trophoblasts.

We examined the capacity of trophoblast-derived interleukin-6 (IL-6) to stimulate secretion of placental hormones, including hCG. IL-6 stimulated hCG secretion by trophoblasts to a level similar to that stimulated by a GnRH analog. The analog, however, released hCG by an IL-6-independent mechanism because PM-1, a monoclonal antibody specific for IL-6 receptors (R), failed to block GnRH-mediated responses, but completely blocked IL-6-mediated hCG secretion, suggesting the existence of two distinct regulatory pathways for hCG release. Immunohistochemical analysis with another IL-6-R-specific antibody, MT-18, showed that IL-6-R was located only on the trophoblast layer of the placenta. Our data revealed the existence of a local regulatory network by which trophoblast-derived IL-6 interacts with IL-6-R on the trophoblasts, resulting in hCG release. Thus, two different regulatory networks, an IL-6 and IL-6-R system and a GnRH and GnRH-R system, regulate hCG release by human trophoblasts independently.

Antibodies, Monoclonal↗
PubMed1990

Site-specific mutagenesis of human chorionic gonadotrophin (hCG)-beta subunit: influence of mutation on hCG production.

The heterodimeric glycoprotein hormones, human chorionic gonadotrophin (hCG), LH, TSH and FSH, consist of two non-covalently linked subunits, the alpha and beta subunits. The beta subunit is specific for each hormone and is responsible for the biological specificity, but the beta subunits of different hormones show some degree of structural homology. The CAGY (cysteine-alanine-glycine-tyrosine) region is one of the amino acid sequences that is homologous in different beta subunits and is highly conserved between species. In the present study, site-specific in-vitro mutagenesis was used to change three individual nucleotides in the centre of the CAGY region of the hCG-beta subunit, and the effects of these mutations on hCG production was determined by in-vitro transcription and then translation in Xenopus laevis oocytes. The results indicate that the CAGY region, particularly the glycine residue at position 36 in the beta subunit, is essential for the production of hCG. This finding is consistent with previous studies showing that this region is necessary for the biological activity of human TSH.

Amino Acid Sequence↗
PubMed1990

Steroid hormones induce macrophage colony-stimulating factor (MCSF) and MCSF receptor mRNAs in the human endometrium.

We investigated the biological effects of sex-steroid hormones, secreted from the corpus luteum and placenta, on the induction of mRNAs encoding macrophage colony-stimulating factor (MCSF) and c-fms proto-oncogene (MCSF receptor) in human endometrium. RNA was extracted from the placenta and endometrium of both pregnant and non-pregnant women, and Northern blot analysis was performed on poly(A)+ RNA using MCSF or c-fms proto-oncogene cDNA as the probe. Results showed: (1) that MCSF mRNA was expressed in the placenta and endometrium of the pregnant uterus, (2) that c-fms proto-oncogene mRNA was also expressed in the placenta and endometrium of the pregnant uterus, and (3) that exogenous sex-steroid hormones could induce the expression of MCSF and c-fms proto-oncogene mRNAs in the endometrium of non-pregnant women. These results indicate that sex-steroid hormones secreted by the corpus luteum and/or placenta influence endometrial and placental growth and differentiation via a mechanism of action involving local production of MCSF and its receptor.

Corpus Luteum↗
PubMed1989

Vertical transmission of human T-cell leukemia virus type I (HTLV-I): detection of proviral DNA in HTLV-I carrier gravida.

The seroprevalence rate of human T-cell leukemia virus type I (HTLV-I) in pregnant women in the Osaka district was determined by enzyme-linked immunosorbent assay and Western blot analysis. Twenty-one (1.0%) of 2192 samples tested were positive for both assays and the seropositive parturients were found to be integrated with HTLV-I proviral DNA in their mononuclear cells by a DNA dot blot hybridization assay using HTLV-I DNA probe or by a selective DNA amplification technique using the polymerase chain reaction (PCR). On the other hand, proviral DNA was not detected in cord blood of the neonates born to the carrier mothers, indicating that transplacental infection of HTLV-I during pregnancy could be excluded. The results support the hypothesis that postpartum infection via breast milk plays a significant role among the possible perinatal transmission routes.

Carrier State↗
PubMed1989

Demonstration of functional immaturity of signal transduction pathways in human cord T cells.

We examined the nature of cytoplasmic signal transduction pathways in cord blood T cells by stimulating them with tumor promoter (TPA) and calcium ionophore (A23187). Costimulation of T cells with TPA and A23187 induced optimal proliferative responses on Day 2 in cord T cells but on Day 4 in adult T cells. The maximal responses observed in cord T cells were much less than those of adult T cells, whereas the Con A-induced proliferative responses of these cells showed no significant differences. The reduced responses of cord T cells were due to their lower efficiency in activating the cellular events in T cell activation and proliferation phase, because cord T cells have significantly less ability than adult T cells to express IL-2 receptor as well as HLA-DR and produce IL-2 molecules, thereby inducing proliferation. These data show immature characteristics of intracellular signal transduction pathways in cord T cells, which are directly related with the functional immaturity of cord T cells.

Adult↗
PubMed1989

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 factor's 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.

Calcimycin↗
PubMed1989

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.

DNA↗
PubMed1989

Impaired susceptibility of human trophoblast to MHC nonrestricted killer cells: implication in the maternal-fetal relationship.

Mammalian pregnancy has frequently been termed "Nature's 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 susceptibilty of trophoblast to MHC nonrestricted killer cells should be functional for the survival of the semiallogeneic fetus.

Cytotoxicity, Immunologic↗
PubMed1989

Trophoblast-derived immunoregulatory factor: demonstration of the biological function and the physicochemical characteristics of the factor derived from choriocarcinoma cell lines.

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-O-tetradecanoyl phorbol 13-acetate and 1 microM 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 physicochemical properties of the choriocarcinoma-derived factor were examined, and the biological significance of the factor during pregnancy was discussed in this paper.

Calcimycin↗
PubMed1989

[Low sensitivity of choriocarcinoma cell lines to tumor necrosis factor (TNF)-alpha].

Sensitivity of cultured choriocarcinoma cell lines to tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma was examined and compared with that of other cultured tumor cell lines. Tumor cells were cultured with 1,000 mu/ml of TNF-alpha and/or 100 mu/ml of IFN-gamma for 24hr. Antitumor effects of the lymphokines were measured by 3H-thymidine uptake and tetrazolium salt (MTT) colorimetric assay. The results revealed that TNF-alpha and/or IFN-gamma had little anti-tumor effect on the choriocarcinoma cell lines tested, while they had cytostatic and cytotoxic effects on other cultured tumor cell lines including Panc-1 (pancreatic carcinoma cell line), Lovo (colon carcinoma cell line) and Ishikawa (uterine endometrial carcinoma cell line). We also examined the effect of TNF-alpha and IFN-gamma on the expression of major histocompatibility complex (MHC) class I antigens in these tumor cell lines by means of cellular binding radioimmunoassay. No enhancing effect was observed on choriocarcinoma cell lines after the treatment with TNF-alpha and/or IFN-gamma. These results suggested the existence of a unique property of choriocarcinoma cells which results in the resistance to host immune attacks.

Choriocarcinoma↗
PubMed1989

[Identification of a human sperm antigen to infertile women's serum and follicular fluid with high sperm immobilizing activity].

In our previous paper, we reported a sperm coating antigen with a molecular weight of approximately 12,000 daltons from sperm membrane fraction by using rabbit anti-seminal plasma antiserum. In this paper, we isolated a human sperm antigen with the same sperm preparation by using sera of infertile women with sperm immobilizing antibody. The isolated antigen showed the following characteristics: (1) It is a glycoprotein with an affinity with lentil lectin and its molecular weight is approximately 15,000 daltons. (2) Little activity of the antigen was seen in seminal plasma. The antigen is localized on the equatorial segment of the acrosome. These facts indicate that the antigen is a genuine sperm antigen and is not a sperm coating antigen. (3) The antigen is bound with the sperm immobilizing antibody in follicular fluid of an infertile woman who has a sperm immobilizing antibody in her serum. This indicates that sperm immobilizing antibody in follicular fluid recognizes the same antigen as in the serum.

Acrosome↗
PubMed1989

[Low susceptibility of choriocarcinoma cell lines to lymphokine activated killer (LAK) cells].

We investigated the anti-tumor effect of lymphokine activated killer (LAK) cells on various carcinoma cell lines as it may play an important role in the immunotherapy of gynecologic cancers. Peripheral blood lymphocytes (PBL) were cultured in 10 U/ml of recombinant interleukin-2 (rIL-2). The cytotoxic action of LAK and natural killer (NK) on carcinoma cell lines was measured by a standard 4-hr 51Cr-releasing assay. Daudi and RPMI 1788, NK resistant B cell lines were lysed by rIL-2 activated PBL although they were not killed by human fresh PBL. LAK cells thus induced were markedly cytotoxic to sixteen carcinoma cell lines. However, five choriocarcinoma cell lines were resistant to LAK action because specific action was less than 30% at effector/target ratio of 20. The cold target competitive inhibition experiments showed that the choriocarcinoma cell line GCH-1 induced much lower inhibition than Daudi cells. These results indicate that the low susceptibility of the choriocarcinoma cell lines to LAK cells could be due to the lack of the effector molecules recognized by killer cells.

Cell Line↗