CX3CR1 and infection: However, on days 2 and 8 post-infection, a significant decrease in the MFI and the relative frequency of CX3CR1+ cells within the F4/80+ macrophage population decreased, from 90 ± 3.69% in uninfected tissue to 44.74 ± 19.53% at day 2 post-infection and 65.39 ± 1.92% at day 8 (Figure 2C).