CXCL9 and pneumonia: Severe pneumonia was associated with overexpression of transcripts of cytokines that activate the CXCR2 receptor pathway, including CXCL1, IL-8, and CXCL5, whereas patients with benign disease presented with a T helper “Th1-Th17” profile, characterized by a significant increase in the expression of CXCR3 pathway activator genes, including CXCL9, CXCL10, CXCL11, and Granzyme B. The expression of IL17A, which is produced by Th17 cells and has been suggested to activate CXCL1 [15,16], was not significantly different between the groups.