3.5 | Analysis of FcεRI expression and surface-bound IgE on basophils
Because correlations were observed between the clinical factors, especially total serum IgE, and responsiveness of basophils, we further examined IgE-related surface markers, including FcεRI expression and IgE expression on basophils. AD patients exhibited higher FcεRI expression on basophils than HCs (P < .001) (Figure 4 A). However, FcεRI had no correlations with clinical/laboratory factors of EASI score, TARC, and LDH (Figure S5). There was a negligible negative trend between FcεRI and serum IgE (rs = −.23) (Figure S5 D). In contrast, despite high serum IgE and higher FcεRI expression on basophils in AD patients compared with HCs, there was no significant difference in surface-bound IgE between AD patient and HCs (P = .52) (Figure 3 B). Moreover, surface-bound IgE had moderate negative correlations with EASI score (rs = −.35) and TARC (rs = −.35) (Figure 5 A, B). Although statistically not significant, there was a trend toward a negative correlation between surface-bound IgE and LDH (rs = −.24) (Figure 5 C). Surface-bound IgE had a strong negative correlation with total serum IgE (rs = −.70) (Figure 5 D). In short, basophils in AD patients, especially in severe AD patients, showed the paradoxical status that surface-bound IgE was kept low despite high FcεRI expression on basophils and high total serum IgE (Figure 1 C, Table S1).