Granulocyte-macrophage colony stimulating factor(GM-CSF) is one of the cytokines which are able to modulate the growth or differentiation of haemopoietic cells. The GM-CSF could not only functionally activate mature white blood cells at an inflammatory site, but could also enhance proliferation and differentiation of progenitor cells into granulocyte or macrophage. It is likely that at the inflammatory sites various cytokines could be produced concomitantly with GM-CSF and those cytokines in concert could modulate the functions of inflammatory cells with various manner such as synergism, additive action, and antagonism etc. In this report, I studied the functional relationship between the biological action of GM-CSF and other inflammatory stimulators by analyzing antimicrobial action of human: promyelocytic cell line assaying [3H] -thymidine incorporated into HL-60, and testing the western blot of released IL-b from murine macrophage cell line RAW264.7.
GM-CSF stimulated an increase in antimicrobial action and growth rate of HL-60 in pararrel at the concentration between 0.1 and 100pM in a dose-dependent manner, although only at the concentration above 10pM, those stimulated effects were statistically significant. Both of undifferentiated HL-60 and mature cells
(differentiated into granulocyte or macrophage) showed enhancement of antimicrobial action with a same degree by treatment with GM-CSF. The combination of various doses of MIP-la and suboptimal dose of GM-CSF resulted in additive enhancement of antimicrobial action of HL-60, and the combination of optimal dose of LPS and various doses of GM-CSF also resulted in additive stimulated effects. However, the combination of suboptimal dose of LPS and suboptimal dose of GM-CSF resulted in synergistic stimulaatory effect on antimicrobial action of HL-60. The release of IL-1b from RAW264.7 was additively increased by combined administration of optimal dose of GM-CSF and
LPS.
These finding taken together suggest that suboptimal doses of GM-CSF and other cytokines potentiate the antimicrobial function of granulocyte by priming them which might amplify the initial defensive reaction at an inflammatory site.
|