IFNG and susceptibility to pneumonia measurement: Given that Chlamydia species are known to upregulate IFN-γ production during infection, and that macrophages in the lung are likely to be primed during pneumonia due to local cytokine production, we felt a comparison of resting BMDM vs. IFN-γ primed the BMDM would enable us to more closely replicate the lung environment during infection in vitro.