Alarmin Signals in ILC2s

Type 2 immune responses protect against worm infections but cause harm in allergies. Group 2 innate lymphoid cells (ILC2s) are key drivers of type 2 inflammation and are activated by the alarmins IL25, IL33, and TSLP. To understand how these signals shape ILC2 function, we performed RNA sequencing of ILC2s lacking alarmin sensing in steady state and under inflammatory conditions. We identified Blimp1 as a transcription factor induced by IL33, essential for cytokine production during worm infection and allergic lung inflammation. Without Blimp1, ILC2s proliferated more but failed to fully differentiate, possibly due to reduced IRF4. This study highlights an IL33-Blimp1 pathway that controls ILC2 effector functions.