While it might be expected that systemic inflammatory changes affect would affect cytokine profiles in the brain, there are reports to the contrary: in systemic clinical infection with increased blood levels of several cytokines, brain extracellular fluid samples showed decreased levels IL-1ra, G-CSF, PDGF-BB, CCL4, and CCL5 (Lassarén et al., 2021). Here, CCL4 is linked to infection.