Kolkhir P, Church MK, Altrichter S, et al. - Researchers focused on the prevalence, role, and significance of eosinopenia in chronic spontaneous urticaria (CSU) by analyzing data from 1,613 patients with CSU from 2 centers. They used automated hematology analyzers to measure peripheral blood eosinophil and basophil counts. They screened the records of patients in order to acquire information on clinical features, outcomes of laboratory tests, the autologous serum skin test, the serum-induced basophil histamine release assay, and response to second-generation H₁-antihistamines and omalizumab. They detected eosinopenia in 10% of patients with CSU. Correlation of blood eosinophil counts with basophil counts was noted, and basopenia was found in 81% of patients with CSU with undetectable eosinophils. Nonresponse to second-generation H₁-antihistamines was better predicted by the combination of eosinopenia and basopenia vs eosinopenia alone. In patients with CSU, findings revealed type IIb autoimmunity, high disease activity, and poor response to treatment in relation to the presence of eosinopenia.