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.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.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).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.