Several chemokines, including CC motif chemokine ligand (CCL) 2, CCL18, CXC motif chemokine ligand (CXCL) 8, and CXCL9 are increased in the BAL fluid (BALF) of HP patients and contribute to the development of the cellular infiltrate and granulomas in HP (16–20). The gene discussed is CXCL9; the disease is hypersensitivity pneumonitis.