PDCD1 and allergic disease: In order to further study how short telomeres protect from HDM‐induced allergy, we studied the expression of several allergic airway inflammation markers such as Il33 (dendritic cell activation), Cd274 (PD‐L1), and Pdcd1 (PD‐1) (Immune checkpoint, T‐cell activation), Cd4 (T‐cell marker), Il4 and Il13 (Th2 cytokines), Tnf and Il1b (Th1 cytokines), Ccl11 (eosinophil chemotaxis), Cxcl1 (neutrophil chemotaxis), and Ccl2 (macrophage chemotaxis) (Figure 3a‐k).