IL4 and asthma: Compared with the control group, asthmatic patients showed increased levels of IL‐2, IL‐4, IL‐5, IL‐6, IL‐10, and IL‐13 in their induced sputum supernatant, and PRB1 protein levels in the sputum supernatant were positively correlated with IL‐4, IL‐5, and IL‐13, which are associated with type 2‐high asthma.