Introduction: Chronic idiopathic urticaria (CIU) is clinically defined as the presence of hives for at least 6 weeks in absence of an identifiable cause. The underlying pathogenesis is unknown thus making the diagnosis and treatment challenging and difficult to standardise. The aim of our study was to investigate the usefulness of two flow cytometic based assays: Basophil enumeration (highly sensitive basophil count, hsBC) and basophil activation test (BAT) in predicting the outcomes of these patients.
Methods: Patients (n=39; 25 female and 14 male, Av age: 40y) were prospectively recruited from the Allergy Clinic at Westmead Hospital, with a reported history of at least 6 weeks of urticaria. All consented patients carefully recorded their symptom scores of wheal number and severity of itch in a diary based on the modified urticaria activity score (MUAS). At baseline all patients were tested for antinuclear antibody (ANA) and antithyroid antibodies (antithyroglobulin and antithyroperoxidase) and specimens referred for hsBC and BAT evaluations.
Patients were requested to maintain their symptom diary for the next 6 week period and then reviewed at 12 weeks. Patients were assigned scores as follow: “0” for asymptomatic, “1” for controlled on antihistamines, “2” for symptomatic on antihistamines and “3” for patients on immunosuppressants.
Results: At both the 6 and 12 week reviews, patients with more active disease with scores of either “2” or “3” showed marked basopenia (median 3.3 and 2.5 cells/μL respectively) compared to those who scored either “0” or 1” (median 13.4 cells/μL at both reviews (p= 0.002). However, BAT using basophils from a non CIU donor and patient’s serum showed no significant up regulation of CD63 or CD203c expression (p=ns). Similarly, the presence of positive ANA and/or thyroid autoantibodies in each of these subgroups was not statistically significant.
Conclusions: We report the novel use of flow cytometric enumeration of basophils as a biomarker of the more severe form of CIU which will likely to be refractory to standard antihistamine therapy.