CXCR2 and clostridium difficile infection: While incubation with CDI-plasma increased neutrophil CXCR2 MFI in whole bone marrow cultures, there was no increase seen when only purified neutrophils were used (Figure 4D), indicating that the effect of plasma from C. difficile-infected mice on the induction of neutrophil CXCR2 requires the presence of other bone marrow cells.