Research Article

Downmodulation of Vaccine-Induced Immunity and Protection against the Intracellular Bacterium Francisella tularensis by the Inhibitory Receptor FcγRIIB

Figure 2

Ft-specific IgA, but not IgG, is significantly increased in FcγRIIB KO versus WT mice following iFt-immunization. FcγRIIB KO and WT mice were immunized i.n. with 20 μL of PBS (vehicle) or 2 × 107 iFt-organisms in 20 μL of PBS on day 0 and boosted on day 21. Serum was then collected on day 35 and levels of total Ft-specific Ab (a), Ft-specific IgG (b), Ft-specific IgG2c (c), Ft-specific IgG1 (d), Ft-specific IgM (e), and Ft-specific IgA (f) were determined via ELISA. Titers of Ft-specific IgG (g) and Ft-specific IgA (h) in BALF were similarly determined. Each symbol represents a single mouse. The 50% maximum of the highest experimental OD was determined and all experimental OD values were transformed to their respective log values. A log (agonist) versus response-variable slope (four parameters) nonlinear regression (curve fit) was performed on the log values, and the unknowns were interpolated. The inverse log was taken on the interpolated unknowns to determine the final titers for each individual mouse sample (error bars represent median with interquartile range of data distribution). Statistics were performed by adding 0.1 to the determined titer value and taking the log of this new value to correct for heteroscedasticity. A one-way ANOVA along with a Tukey’s multiple comparison test was performed, and median and interquartile range is graphed. ; .