CALCA and infection: The following observations support this finding: (i) Mice with a myeloid-specific knockout of KLF4 showed an impaired early pro-inflammatory immune response as reflected by reduced levels of pro-inflammatory cytokines (TNF-α, KC, IL-1β) and increased levels of the anti-inflammatory cytokine IL-10 in plasma and BALF and an impaired bacterial clearance from the lungs 24 hours after infection with S. pneumoniae.