Previous findings in related models33, 39–42 suggest these CD4-Il17+ cells to be γδ T cells, a population of innate immune cells capable of rapidly producing Il17 upon stimulation; although other lymphocyte sources of Il17 include NKT43 or CD8+ cells44, therefore Il17 sources, apart from Th17 cells, and their contribution to pneumonitis with fibrosis, if any, remain to be elucidated. Here, CD4 is linked to pneumonitis.