IL1RL1 and asthma: One of these clusters is significantly increased in HDM-sensitive asthmatics compared with HDM-sensitive non-asthmatics, and these “asthma-associated” Th2 cells are highly enriched for expression of IL5, IL9, PPARG (a transcription factor linked to IL-9 production), GZMB (encoding for the cytotoxic molecule granzyme B), IL17RB, and IL1RL1 (the gene encoding IL-33R/ST2).