We used acute infection with M. pneumoniae, and this modality results in a Th1-type immune response (Fonseca-Aten et al., 2005; Hardy et al., 2001), so we screened for the presence of the Th1 cytokines IFN-γ, TNFα, functional IL-8 (CXCL1) in BALF following infection. This evidence concerns the gene CXCL1 and infection.