CCR2 and infection: Subsequent analysis of Ly6C+CCR2+CX3CR1+/- monocytes on day 3 post-challenge, when monocytes represent the majority of infected mononuclear cells, revealed MHCII expression was significantly reduced on RFP+ versus RFP- monocytes from NaLm mice but this difference was lost by day 6 (Fig 4G and 4H, far left panel), suggesting early modulation of monocyte maturation by Leishmania during acute primary infection.