Shigeru Yamaga

Stimulatory effects of bestatin on human B-cell colony formation

Bestatin, (2S, 3R)-3-amino-2-hydroxy-4-phenylbutyryl-L-leucine, is a small molecular immunomodifier. Effects of this compound on human immune function were studied, in vitro, using the human B-cell colony formation technique. B-cell colonies were obtained from enriched B-cell populations placed in conditioned methylcellulose medium containing stimulators and irradiated T-cells as feeders. Addition to the culture of Bestatin at concentrations of 0.1 microgram/ml and 1 microgram/ml led to a significant increase (P less than 0.05) in the number of B-cell colonies and this effect was abolished when irradiated T-cells were not added to the culture. Bestatin increased soluble factor production induced by phytohemagglutinin (PHA)-stimulated T-cells. Such findings suggest that T-cells probably mediate this stimulatory effect of Bestatin on B-cell colony formation.

CD7-positive acute myeloid leukemia : further evidence of cellular immaturity

SummaryAmong 63 cases of acute myeloid leukemia (AML), 14 were found to express the CD7 antigen, a cell surface marker usually found at an early stage during T lineage differentiation. The CD7-positive AML cases consisted of 5 cases of M1, 3 cases of M2, 3 cases of M4, 1 case of M5, 1 case of M6 and 1 case of M7. Among these 63 cases, the proportion of blast cells expressing the CD34 antigen was examined. The proportion of CD34-stained cells among the CD7-positive AML cases, although varying, was significantly larger than that among the CD7-negative AML cases (P<0.05). As the CD34 antigen was expressed on hematopoietic progenitor cells and was considered to reflect an early hematopoietic stage, the high proportion of cells expressing CD34 among the CD7-positive AML cases may support the notion that CD7-positive AML cells are immature.

Measurement of human granulocyte-macrophage colony-stimulating factor (GM-CSF) by enzyme-linked immunosorbent assay

SummaryAn IgG monoclonal antibody against recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), designated HGMI, was produced by fusion of immune mouse splenocytes with HAT-sensitive murine myeloma cells. A sandwich enzyme-linked immunosorbent assay (ELISA) for measurement of human GM-CSF was developed using this HGMI and a polyclonal antibody against GM-CSF raised in a rabbit. GM-CSF in culture supernatants of phytohemagglutinin (PHA)- or concanavalin A (Con A)-stimulated peripheral blood mononuclear cells (PBMC) were measured by this ELISA system and the conventional CFU-GM colony formation method. The data indicated that the ELISA was highly efficient and sensitive for the detection of as little as 50 pg/ml recombinant GM-CSF. The CFU-GM colony assay may be influenced by other cytokines which can enhance or suppress colony formation, and ELISA for GM-CSF is more useful for kinetic studies of precise levels of production from PBMC.

THE EFFECTS OF RECOMBINANT HUMAN GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR ON THE INDUCTION OF LYMPHOKINE-ACTIVATED KILLER CELLS IN VITRO

Granulocyte-macrophage colony-stimulating factor (GM-CSF) was added to a culture of human peripheral blood mononuclear cells in the presence of interleukin 2 (IL-2) in vitro to elucidate its effect on the induction of lymphokine-activated killer (LAK) cells. Viable cell counts of cultured cells and their cytotoxic effects against natural killer (NK) cell-resistant Daudi cells and NK cell-sensitive K562 cells were measured using the trypan blue dye exclusion test and a 51Cr release assay from the tumor cells, respectively. Although GM-CSF alone did not influence either the cytotoxicities or the surface phenotypes of the cultured cells, the viable cell counts were significantly increased by the addition of GM-CSF in the presence of IL-2 (P less than 0.01). These findings indicate that the addition of GM-CSF in the presence of IL-2 during the induction of LAK cells is useful for obtaining a larger number of effector cells which possess substantial cytotoxic activity.