According to a current study of the Medical University Vienna, specialised T memory lymphocytes in the lungs that react to inhaled allergens, cause attacks of allergic asthma. These T-helper 2-tissue resident memory cells, which are located in the lungs for a lifetime are known as Th2-TRMs, and are responsible for asthma sufferers having asthma attacks shortly after they come in contact with allergens that they are allergic to and that these attacks can occur throughout their entire life.
source https://www.lifetechnology.com/blogs/life-technology-news-blog/the-lungs-never-forget-specialised-t-cells-remember-allergens