These differences in the number of hematopoietic cells support the different patterns of circulating cytokine expression after infection, with Rag2-/- mice showing reduced levels of IFN-γ, IL-6, CCL2, CXCL1, and CXCL10, but an important increase of TNF-α and IL-1β levels. This evidence concerns the gene CXCL1 and infection.