The finding that IL‐18 eliminated MFI of IL‐18R in mouse blood neutrophils and IL‐18R+ monocytes in mouse blood suggests that IL‐18 can down‐regulate expression of its own receptor, which may represent a self‐elimination mechanism of IL‐18, supporting the view that an IL‐18/IL‐18R imbalance decides the role of IL‐18 in the pathogenesis of asthma. Here, IL18R1 is linked to asthma.