Fig. 3. Effects of Fusobacterium nucleatum on IL-8 and IL-6 production by two respiratory epithelial cell lines. Human alveolar (A549) (a) and pharyngeal (Detroit 562) (b) epithelial cells were incubated with heat-inactivated F. nucleatum at 1 × 10⁸ CFU/ml for 12 h. IL-8 and IL-6 protein levels in the cell culture supernatants were determined using ELISA and expressed as pg/ml. Data are presented as the mean ± SD. *; a value below the detection limit.