AHR and allergic asthma: The activation of ADRB2 on human peripheral blood lymphocytes enhances IL-13 production (42), and studies have found that ADRB2 is required for mucus metaplasia, AHR and lung inflammatory cells in asthma models (43), and that the prolonged use of ADRB2 blockers could relieve allergic asthma (44, 45).