Thoracic irradiation resulted in an eight to ten fold increase in the total number of cells infiltrating the lungs of the strains of mice succumbing to pneumonitis with fibrosis (C57BL/6J and Tlr2/4−/− mice) with the influx evident at 20 and 26 weeks post irradiation, as presented in Table 1. This evidence concerns the gene TLR2 and fibrosis.