Rat splenocytes control intramacrophage <i>Francisella</i> growth that is accompanied by IFN-γ and NO production.

<p>BMMΦ from Fischer 344 rats were infected with LVS (Macs), and co-cultured with naïve splenocytes or with immune splenocytes derived from LVS-vaccinated rats. Decreasing numbers of splenocytes were added to a constant number of confluent LVS-infected macrophages, where 1 = 5 x 10⁶, 1/2 = 2.5 x 10⁶, 1/4 = 1.25 x 10⁶, 1/8 = 0.625 x 10⁶, 1/16 = 0.312 x 10⁶, 1/32 = 0.156 x 10⁶ splenocytes. After three days of co-culture, BMMΦ were lysed to evaluate the recovery of intracellular bacteria (Panel A). Values shown are the mean numbers of CFU/ml ± SD of viable bacteria from triplicate wells. Supernatants were collected for analyses of IFN-γ by ELISA (Panel B) and NO by Griess reaction (Panel C), and concentrations of each were calculated using standard curves as references. Values shown are the mean concentration ± standard deviation of triplicate wells. Brackets indicate a significant difference (<i>P</i> < 0.05) between the recoveries of bacteria from macrophages in co-cultures or production of IFN-γ and nitric oxide.