Impaired macrophage activation in vitamin D3 deficiency: differential in vitro effects of 1,25-dihydroxyvitamin D3 on mouse peritoneal macrophage functions.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) is known to interact in vitro with mononuclear phagocytes. The purpose of this study was to determine the role of the steroid in macrophage activation in vivo. Peritoneal macrophages from normal and vitamin D3-deficient mice were obtained after i.

Differential induction of monocytic functions by dibutyryl cyclic AMP and retinoic acid in a human monoblast cell line U937.

Differentiation-inducing agents have recently been applied clinically in various myeloproliferative diseases, based on their in vitro ability to induce differentiation in myeloid and monocytic cell lines. In this study we compared the abilities of two agents, dibutyryl cyclic AMP (DBcAMP) and retinoic acid (RA) to induce monocytic functions in the human histiocytic lymphoma cell line U937. Both agents produced similar induction of phagocytosis and reduction of nitroblue tetrazolium (NBT).

Expression of granulocytic functions by leukemic promyelocytic HL-60 cells: differential induction by dimethylsulfoxide and retinoic acid.

Recently, a novel approach has been used in the treatment of leukemia: induction of the leukemic cells to undergo terminal differentiation. Based on its in vitro ability to induce differentiation in several myeloid leukemic cell lines, retinoic acid (RA) has been applied clinically in cases of myelodysplastic syndromes and acute myeloid and promyelocytic leukemia. In the present study we have determined in detail the ability of RA to induce expression of granulocytic functions in a human promyelocytic leukemia cell line (HL-60) and compared it with that of dimethylsulfoxide (DMSO).

Production of C5a antagonist by synovial and peritoneal tissue fibroblasts.

Fibroblasts grown from synovial and peritoneal tissues release into the medium an inhibitor of neutrophil chemotaxis. The inhibitor resembles the antagonist previously described in synovial and peritoneal fluids. It is a heat stable (56 degrees C) protein of MW approximately 40 kDa that counteracts the chemotactic activity of zymosan-activated serum or purified C5a but not the peptide chemoattractant F-met-leu-phe.