TLR2 and pulmonary fibrosis: Given the increased frequency of neutrophils detected in the lavage of mice presenting significant pulmonary fibrosis (Tlr2,4−/− mice at 20 weeks post irradiation and C57BL/6J mice at 26 weeks) we investigated the association of these traits and identified the frequency of PMNs in lavage at the time of distress to be significantly correlated with extent of fibrotic lung disease (correlation coefficient = 0.72, p value = 0.00024, Fig. 3b).