CD4 and allergic disease: On the other hand, it has been described that CD25 is the alpha subunit of IL2R and its expression has been related to activation status of T cells [26]; interestingly, in this study, the frequency of PBMC expressing this cell surface marker was significantly elevated in PAC patients group in contrast to healthy individuals, suggesting that PBMC and circulating CD4+ T cells are in an activation status, as similarly reported in other allergies like asthma [27, 28] rhinitis [28], and dermatitis [29].