Strain dependent pulmonary T helper cell populations in acute radiation response. Mice were exposed to 18 Gy of thorax irradiation and euthanized at 6 hours, 1 day and 7 days post treatment. A) Th1 (CD4 + Ifnγ+), Th2 (CD4 + Il13+) and Th17 (CD4 + Il17+) cell counts were measured by flow cytometry. Mean ± SE of T helper cells among 106 total lung cells, for groups of 4–5 mice. Significant variation in inbred strain measures by ANOVA indicated. B) Linear regression of the pulmonary fibrosis score against the numbers of CD4 + Ifnγ + and CD4 + Il17+ cells recorded at the day 7 time point. A significant interaction (p = 0.04) between the CD4 + Il17+ and CD4 + Ifnγ + cell counts is indicated by the intersecting regression lines of the fibrosis score against each individual variable.