FIG. 3.

TNF-α is induced by flagellin in the BALB/c lung. (A) Groups of four to seven BALB/c mice were i.t. instilled with 1 μg of purified flagellin or the inactive mutant flagellin 229 in a total volume of 50 μl of pyrogen-free PBS. At the indicated times postinstillation, BALF was collected for analysis of TNF-α production by ELISA. Bars represent means. An asterisk indicates statistical significance from time zero (P < 0.01) or 229 treatment (P < 0.05). (B) The lungs of BALB/c mice in groups of six were i.t. instilled with PBS alone or 1, 5, or 15 μg of flagellin. At 4 h, BALF was collected and analyzed for TNF-α production. Bars indicate means, and an asterisk indicates significance over the value obtained with 1 μg of flagellin. All doses were statistically greater than with PBS. (C) The lungs of BALB/c mice in groups of five were instilled with PBS alone, 1 μg of Salmonella flagellin, or 1, 10, or 20 μg of recombinant Pseudomonas strain PAO1 or EPEC flagellin. TNF-α in the BALF was determined at 4 h postinstillation by ELISA. Bars indicate standard errors, and an asterisk indicates significant difference from the value obtained with 1 μg of Salmonella flagellin. The F test for equality of variance and Student's one-sided t test were used to assign statistical significance at P values of <0.05 or <0.01.