Further experiment of flow cytometry and immunohistochemistry identified bronchiolar progenitors found by Stripp and colleagues as the OX40Lpos non‐hematopoietic cells that not only increase in number but also induce OX40L expression on their surface upon respiratory infection with influenza A virus (Teisanu et al, 2009, 2011). The gene discussed is TNFSF4; the disease is respiratory tract infectious disorder.