Eosinopenia, in Chronic Spontaneous Urticaria, Is Associated with High Disease Activity, Autoimmunity, and Poor Response to Treatment.

BACKGROUND

Chronic spontaneous urticaria (CSU) is characterized by the degranulation of skin mast cells and the influx of basophils and eosinophils to affected skin sites. Blood basopenia has been linked to severe antihistamine-resistant CSU and type IIb autoimmunity, whereas the role of eosinophils in CSU is largely unknown.

OBJECTIVE

To analyze data from 1613 patients with CSU from 2 centers to study the prevalence, role, and relevance of eosinopenia in CSU.

METHODS

Peripheral blood eosinophil and basophil counts were measured by automated hematology analyzers. Patient files were screened for clinical characteristics, results of laboratory tests, the autologous serum skin test, the serum-induced basophil histamine release assay, and response to second-generation H-antihistamines and omalizumab.

RESULTS

Ten percent of patients with CSU had eosinopenia. Eosinopenia was associated with the female sex, high disease activity, autologous serum skin test and basophil histamine release assay positivity, low total IgE, and high levels of C-reactive protein and IgG-antithyroperoxidase (P ≤ .007). Nonresponders to second-generation H-antihistamines or omalizumab had significantly lower eosinophils as compared with responders (P < .05 and P < .01, respectively). Blood eosinophil counts correlated with basophil counts (r = 0.396; P < .001), and 81% of patients with CSU with undetectable eosinophils had basopenia. The combination of eosinopenia and basopenia is a better predictor of nonresponse to second-generation H-antihistamines than eosinopenia alone (odds ratio of 9.5 vs 4.8).

CONCLUSIONS

Eosinopenia in patients with CSU is associated with type IIb autoimmunity, high disease activity, and poor response to treatment. Eosinophils should be explored as biomarkers and investigated for their contribution to the pathogenesis of CSU.