CCL22 and parasitic infectious disease: Further, the increased expression of IFN-γ, T-bet, STAT1, CCL5, and CXCL9 genes associated with M1 polarization of macrophages, along with the downregulation of Arg-1, CCL17 and CCL22 genes, a characteristic of M2 polarization of the macrophages43, indicates that LmCen−/− immunization biases toward the M1 phenotype in vaccinated animals, and suggests that macrophages play an important role in the LmCen−/− mediated immune response to control parasitemia.