The observation that the lung phenotype of TLR2−/− or TLR4−/− mice did not differ from C57BL/6 wildtype (WT) mice revealed that the single knockout mice (TLR2−/− or TLR4−/−) have similar sensitivity to WTI-induced alveolitis and fibrosis as WT mice. The gene discussed is TLR4; the disease is hypersensitivity pneumonitis.