Isolation of Group 2 Innate Lymphoid Cells from Mouse Lungs

: The recently described group 2 innate lymphoid cells (ILC2) exert critical roles in type 2 immune responses, epithelial repair at mucosal tissues and metabolic homeostasis. ILC2 release large amounts of type 2 cytokines such as interleukin 4 (IL-4), IL-5, and IL-13, driving type 2 immunity such as the defense against helminths. However, if not tightly regulated ILC2 can trigger unwanted type 2 immunopathologies including allergic airway inflammation, airway hyper-responsiveness, and atopic dermatitis. Viral respiratory tract infections, archetypal triggers of type 1 immune responses, often give rise to pulmonary type 2 immunopathologies such as asthma and asthma exacerbations. Interestingly, pulmonary viral infections induce the release of IL-33, followed by induction of ILC2-mediated pulmonary type 2 immunopathology independent of the adaptive immune system. Due to their scarcity at steady state but also after infection and inflammation, pulmonary ILC2 are challenging to work with. In this chapter, we describe the detection and isolation procedure of pulmonary mouse ILC2 by flow cytometry and compare four distinct enzymatic mouse lung tissue processing protocols for optimized cell yield.