M. Enomoto

Human Macrophage Colony-Stimulating Factor Induces the Differentiation of Trophoblast

When human cytotrophoblastic cells in the early stage of pregnancy were cultured in a serum-free medium in the presence of human macrophage colony-stimulating factor (M-CSF), the cytotrophoblastic cells fused and formed a typical syncytiotrophoblast which had a dense distribution of microvilli revealed under an electron microscope. On the other hand, cytotrophoblasts incubated with anti-M-CSF antibody showed hardly any syncytiotrophoblast formation. Following this finding, we studied the differentiation of chorionic cells from the viewpoint of hormone secretion. When cytotrophoblasts were incubated in the presence of M-CSF, the supernatant of the culture showed an increase in human chorionic gonadotropin and human placental lactogen levels in proportion to the concentration of M-CSF added. When cytotrophoblasts were incubated in the presence of anti-M-CSF antibody or anti-fms antibody, human chorionic gonadotropin and human placental lactogen secretion were suppressed. Thus, M-CSF was morphologically and endocrinologically found to induce the differentiation of chorionic cells.

T‐Cell Receptors Are Expressed but Down‐Regulated on Intradecidual T Lymphocytes

PROBLEM: Dietl et al. considered “intradecidual T cell tolerance towards fetal antigens” with their observation that intradecidual T cells lack immunohistochemically detectable amounts of T cell receptor (TCR) molecules while expressing normal amounts of CD3 molecules during early normal pregnancy.

A study of CD45RO, CD45RA and CD29 antigen expression on human decidual T cells in an early stage of pregnancy.

The decidua is the place where the fertilized egg is implanted and where the immunocompetent cells of the mother come into direct contact with genetically disparate cells of the conceptus. Although the T cells in the decidua are exposed to fetal antigens, the fetus is not rejected by maternal immunocompetent cells. In the present study, we examined surface markers to determine whether the T cells in the human decidua are naive T cells without or memory T cells with a history of antigen stimulation. Although few T cells were present in the decidua, as compared to the peripheral blood, CD45RO+, CD29+ and CD45RA- CD4+ T cells as well as CD45RO+, CD29+ and CD45RA- CD8+ T cells, which are considered to be memory T cells, were in the majority, with only small numbers of CD45RO-, CD29- and CD45RA+ CD4+ and CD8+ cells, which are naive T cells, present. Also, the decidual mononuclear cells secreted IL-2 and IL-4. Since IL-4 is secreted only by memory T cells, it is suggested that in the decidua memory T cells increase in number and secrete cytokines, thereby in some way influencing the phenomenon of fertility.

Macrophage Colony-stimulating Factor Induces the Growth and Differentiation of Normal Pregnancy Human Cytotrophoblast Cells and Hydatidiform Moles but Does Not Induce the Growth and Differentiation of Choriocarcinoma Cells

In the present study, we examined whether or not macrophage colony‐stimulating factor (M‐CSF; CSF‐1) is involved in the growth and differentiation of human chorionic, hydatidiform mole and choriocarcinoma cells. M‐CSF promotes the growth of early gestation chorionic cells, hydatidiform mole cells, and a human term placenta cell line (tPA30‐1). However, the growth of choriocarcinoma cells, BeWo, Jar, Jeg‐3, and NUC‐1, was not influenced at all by M‐CSF. M‐CSF promoted the secretion of human chorionic gonadotropin (hCG) and human placental lactogen (hPL), which are secreted from differentiated trophoblast, from early gestation chorionic cells and from hydatidiform mole cells. However, the secretion of hCG and hPL from choriocarcinoma cells was not affected by M‐CSF. When M‐CSF localization was examined by immunohistochemical staining, M‐CSF was detected in chorionic and hydatidiform mole cells, but was absent in choriocarcinoma cells. These results suggest that the growth and differentiation of normal chorionic and hydatidiform mole cells are M‐CSF‐dependent, while the growth and differentiation of choriocarcinoma cells are not.

LOCALIZATION OF STEM CELL FACTOR (SCF) AND c-kit mRNA IN HUMAN PLACENTAL TISSUE AND BIOLOGICAL EFFECTS OF SCF ON DNA SYNTHESIS IN PRIMARY CULTURED CYTOTROPHOBLAST

The supernatant of homogenized human placental tissues at early and late stages of pregnancy were found to contain 40-100 pg of stem cell factor (SCF)/mg of total protein by enzyme linked immunosorbent assay. When the SCF mRNA expression was examined by reverse transcriptase-polymerase chain reaction (RT-PCR), the secretory type and membrane-bound type SCF mRNA were detected in the human placental tissues in the early stages of pregnancy and in a human placental cell line;tPA30-1 cells. However, the secretory type SCF mRNA was predominant and membrane-bound type SCF mRNA was absent or very weak in the term placental tissues. When the distribution of SCF mRNA and c-kit mRNA in the placental tissues was examined by in situ hybridization, SCF mRNA was detected in the cytotrophoblast, the intermediate trophoblastic cell column and the stromal cells, while c-kit mRNA was detected in the cytotrophoblast and the intermediate trophoblastic cell column. Both c-kit and SCF mRNA were absent or very weak in the syncytiotrophoblasts. The supernatant of primary cultured cytotrophoblasts and tPA30-1 cells were found to contain SCF. In cytotrophoblasts in the early stage of pregnancy cultured in the presence of recombinant human secretory type SCF, DNA synthesis was increased depending on the SCF concentration. These findings indicate that SCF is a cytokine which promotes the growth of placental cells by the autocrine and paracrine mechanism.