For example, exposure of mice preadministered intranasal gamma herpes virus to a subsequent allergen reduced asthma severity, due to the activity of resident alveolar macrophages.[38] In addition, infection with respiratory viruses can result in innate immune memory in alveolar macrophages with the help of CD8 T cells, but not with bone marrow progenitors.[39] Various macrophage subpopulations are thought to be specifically involved in the course of lung tissue damage after β‐glucan pretreatment. This evidence concerns the gene CD8A and infection.