TNF and hypersensitivity pneumonitis: Although IFN-γ, IL-12, and TNF-α, which were shown to be involved in the pathogenesis of HP in animal models and in vitro experiments [11,12], did not reach detectable values in the BALF of our patient, the high level of IL-8, which is a chemoattractant for T lymphocytes and neutrophils, was consistent with that in patients with HP [8].