CXCL9 and hypersensitivity pneumonitis: While WT mice show the production of IP-10/CXCL10, Mig/CXCL9, and I-TAC/CXCL11 during the development of the classic HP reaction, GKO mice have reduced or no levels of IP-10/CXCL10, Mig/CXCL9 and I-TAC/CXCL11 in the lungs and reduced T-cell alveolitis in response to SR exposure.