Dietary fish oil supplementation alters LTB4:LTB5 ratios but does not affect the expression of acute graft versus host disease in mice.

One of the mechanisms by which corticosteroids may modify acute graft vs host disease (GvHD) is via inhibition of arachidonic acid (AA) metabolism. Leukotriene B4 (LTB4) is a product of that pathway which may take part in the pathogenesis of GvHD through the stimulation of T-lymphopoiesis and T-lymphocyte activation. LTB4 is a metabolite of AA (20:4n-6).

Hematopoietic growth factor induction of gamma-glutamyl transferase in the KG-1 myeloid cell line.

The enzyme gamma-glutamyl transferase (GGT) is a multifunctional enzyme that participates in a number of metabolic processes, including the conversion of leukotriene C4(LTC4) to leukotriene D4(LTD4). LTD4 is necessary for normal myeloid proliferation and differentiation. We have examined the ability of hematopoietic growth factors (HGF) to induce GGT enzyme activity and mRNA content in a HGF-responsive cell line (KG-1).

Histochemical quantitation of gamma-glutamyl transferase in human leukemia cell lines.

The enzyme gamma-glutamyl transferase (gamma-GT) is involved in many biochemical systems, including the signal transduction of hematopoietic growth factors. Standard colorimetric gamma-GT assays require larger cell numbers than may be obtainable in many cases, such as with highly purified stem-cell populations. To study gamma-GT expression in limited populations, we used a histochemical stain to analyze gamma-GT semiquantitatively in cells of hematopoietic origin.

Regulation of HL-60 differentiation by lipoxygenase pathway metabolites in vitro.

We have studied the effects of lipoxygenase inhibition and metabolite addition of HL-60 cells induced to differentiate. When HL-60 are induced by dimethyl sulfoxide (DMSO) in the presence of an inhibitor of lipoxygenase, caffeic acid, there is a marked change from the expected phenotype of mature granulocytes to a population composed predominantly of mature monocytes. (DMSO alone: 54% granulocytes, 10% monocytes; DMSO + caffeic acid: 23% granulocytes, 53% monocytes.

Effects of lipoxygenase and glutathione pathway inhibitors on leukemic cell line growth.

We have examined the effects of various inhibitors of the lipoxygenase pathway of arachidonic acid metabolism on the growth of three well-characterized human leukemia cell lines, HL-60, K-562, and KG-1. An intact lipoxygenase pathway, and the synthesis of leukotriene C4 (LTC4), which requires reduced glutathione, is essential for in vitro growth of normal myeloid progenitors (CFU-GM). We tested the effects of nordihydroguiaretic acid (NDGA) and caffeic acid (CA), inhibitors of lipoxygenase; buthionine sulfoximine (BSO), which inhibits glutathione synthesis; and Acivicin, a glutamine antagonist, on these cell lines and compared the effects with those seen on CFU-GM.