CD274 and Allergy: In fact, such axis showed to play a crucial role in autoimmunity,10 tumour immunity,11 infectious immunity12 and allergy.13 PD‐L1 is commonly expressed in some healthy tissues since it is involved in the normal immunological homeostasis.14 However, in many types of cancer, the expression of PD‐L1 on tumour cells is remarkably higher.