Mami Saito

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.

Enhancing effects of human macrophage colony-stimulating factor on the secretion of human chorionic gonadotropin by human chorionic villous cells and tPA30-1 cells

Human macrophage colony-stimulating factor (hM-CSF) concentration-dependently enhanced the secretion of human chorionic gonadotropin (hCG) by primary cultured human cytotrophoblastic cells and a human placental cell line, 3A-SubE (tPA30-1). Since this effect appeared 12 hours after the addition of hM-CSF and disappeared when protein synthesis was inhibited, it was surmised that hCG synthesis was enhanced by hM-CSF. When anti fms (hM-CSF receptor) antibody was added, hCG secretion by cultured human cytotrophoblasts in early pregnancy markedly decreased. These findings demonstrate that hM-CSF acts on the chorionic villous cells and promotes hCG synthesis by these cells.

Production of IL-6 (BSF-2/IFN β2) by mononuclear cells in premature and term infants

The production of interleukin 6 (IL-6) was examined in premature neonates (48 cases, including 3 miscarried fetuses) and fullterm neonates (20 cases). The IL-6 production by mononuclear cells was measured after stimulation with Staphylococcus aureus Cowan Strain I (SAC), phytohemagglutinin (PHA) or lipopolysaccharide (LPS). The production in full-term neonates was similar to that in healthy adults, whereas it was significantly lower in premature neonates without premature rupture of the membrane (PROM). However, in premature infants with PROM a normal level of IL-6 production was observed in mononuclear cells stimulated with SAC, PHA and LPS. Furthermore, there was a positive correlation between the IgM concentration in the cord serum and IL-6 production by LPS-stimulated mononuclear cells.

Interleukin-2 production by human fetal lymphocytes

IL-2 production by PHA-stimulated human lymphocytes in umbilical blood was studied ontogenetically. Lymphocytes from the 16-week-old fetus produced appreciable amounts of interleukin-2 (IL-2). In 16- to 36-week-old fetuses the IL-2 production rate was found to be significantly higher than that in adults. When signal transduction, which is mediated by high affinity IL-2 receptors (IL-2R), was studied after adding exogenous IL-2 to PHA-blast lymphocytes, the response of the 24-week-old fetus was similar to that of adults. These results indicate that the attainment of IL-2 production and the function of IL-2 receptors are completed at a relatively early stage of fetal development.

IL-2 receptor expression and function on human cord blood mononuclear cells following PHA and anti-CD3 antibody stimulation

Interleukin-2 receptors (IL-2R) on mononuclear cells from human umbilical cord blood were investigated after stimulation by phytohemagglutinin (PHA) and anti-CD3 antibody. The proportion of cells expressing the Tac antigen (IL-2R alpha, p55) did not differ from that for adult mononuclear cells. However, the levels of high affinity IL-2R (H-IL-2R) and low affinity IL-2R (L-IL-2R) present on the PHA blasts of cord blood cells were shown to be twice and three times, respectively, that of adults by interleukin-2 (IL-2) binding assay. The level of low affinity IL-2R in the cord blood cells was approximately double that of adult cells after activation by anti-CD3 antibody, but no difference was observed in the levels of high affinity IL-2R. Functional investigation of IL-2R revealed that the amount of internalized IL-2 in PHA-stimulated cord blood mononuclear cells was twice that in adult mononuclear cells but there were no differences between them in the time course of internalization and degradation. Although there were significant numbers of H-IL-2R in premature (25 and 28 weeks) infants following PHA stimulation, there were markedly fewer following anti-CD3 stimulation. Prematurity of the T-cell activation system through the CD3 pathway at this stage is therefore indicated.