Effect of 405 nm on IL-6 production in C. trachomatis -infected epithelial cells. (A) HeLa cells were infected with C. trachomatis serovar E at a MOI of 5 (CTE5). (B) Infected cells were then exposed to varying doses of 405 nm at a range of energy densities (5-20 J/cm2) either promptly after infection or 24 h post-infection (post-24 h). The effect of 405 nm on IL-6 production was assessed during active (A and B) and penicillin-induced persistent stages (C). Supernatants were collected and measured for IL-6 production using an ELISA. Treatments are grouped based on post-hoc comparisons for convenience. Mean ± SEM are plotted for the two replicated experiments. Statistical differences were determined post-hoc using a Bonferonni adjustment comparing all groups to C. trachomatis infected cells (CTE); *, P < 0.05; ** P < 0.005.