REGULATION OF INTERLEUKIN-6, AND MACROPHAGE-COLONY-STIMULATING FACTORMESSENGER-RNA LEVELS BY HISTAMINE IN STROMAL CELL-LINE (MC3T3-G2 PA6)/

Objective: The aim of this study was to examine the role of histamine in regulation of IL-6 and M-CSF gene expression in bone marrow stromal cells. Total cellular synthesis was also estimated for IL-6. Material s: The effects of the amine were evaluated using the stromal cell line , MC3T3-G2/PA6 (PA6). Results: Histamine caused a distinct accumulatio n of IL-6 mRNA in the cells, whereas it decreased M-CSF transcripts. B oth pyridylethylamine, a H-1 agonist, and dimaprit, a H-2 agonist, cau sed a large increase in the level of IL-6 mRNA in PA6 cells. The hista mine-induced expression of IL-6 mRNA was associated with enhanced secr etion of IL-6, as determined by ELISA. Conclusions: These results, tog ether with the results of our previous studies, suggest that histamine produced by stromal macrophages differentially regulates the producti on of IL-6 and M-CSF in other kinds of stromal cells and hence promote s differentiation and/or proliferation of hematopoietic progenitor cel ls.