These OX40L-related T-cell regulatory roles include the ability of lung ILC2s to promote local T-cell responses to infections and allergens114–116, as shown by the fact that lung ILC2s express high levels of OX40L after intranasal administration of papain or IL-33 and promote the expansion of OX40-expressing Th2 cells. The gene discussed is TNFSF4; the disease is infection.