CXCL13 and infection: Downregulation of the CXCL1/2/5-CXCR2 axis, as demonstrated in the CXCL5-/- infection mouse model and the CXCR2 blockade model, enhanced CXCL13 expression in infected lungs as soon as during the innate immunity stage (Figures 6A, C and Figures 7B, C).