Objective: To investigate the effect of one of the acute-phase proteins, fibrinogen, on the release of IL-1beta and -8 by human peripheral polymorphonuclear leukocytes (PMN) and the possible role of fibrinogen during the destruction of periodontium.
Methods: Peripheral PMN were isolated by discontinuous density gradient centrifuging technique. The freshly isolated PMN were suspended in Hank's balanced saline solution (1 x 10(9)/L) supplemented with 0.5% BSA and 0.1% glucose. The levels of IL-1beta and -8 in the supernatants produced by cultured cells upon the addition of human fibrinogen at different concentrations were measured by ELISA technique.
Results: Incubated with human fibrinogen at 2 g/L or 10 g/L for different time periods, human peripheral PMN released significantly greater amount of IL-1beta [(10.41 +/- 0.37) - (35.86 +/- 0.30) ng/L or (22.81 +/- 0.45) - (57.77 +/- 2.08) ng/L] and IL-8 [(93.90 +/- 13.95) - (2045.66 +/- 53.03) ng/L or (115.02 +/- 10.61) - (3858.69 +/- 25.65) ng/L] than PMN without the stimulation of fibrinogen (IL-1beta, P < 0.001, and IL-8, P < or = 0.016). The higher concentration of fibrinogen or the longer treatment time, the higher levels of IL-1beta and -8 were released by PMN (P < 0.001).
Conclusions: Fibrinogen induced the secretion of pro-inflammatory cytokines IL-1beta and -8 by PMN and may be involved in magnification of the inflammatory response of periodontium and bone resorption.