CXCL9 and Q fever: No significant difference in antigen-specific IFNγ and IL-2 production, and IFNγ/IL-2 ratio, was found between QFS patients and asymptomatic Q fever seropositive controls, or in antigen-specific IL-2, CXCL9, and CXCL11 production between QFS patients with persisting complaints and QFS patients who recovered from their complaints.