The Role of antiFcεRIα Autoantibodies Detection and Autologous Serum Skin Test in Comparison To Histamine Release Assay in Diagnosis of Chronic Autoimmune Urticaria.

Chronic autoimmune urticaria is manifested by wheals and itching for 6 weeks, which is mediated mainly by autoantibodies against IgE receptors (FcεRIα). We aimed to assess the role of IgG autoantibody against FcεRIα in combination with autologous plasma skin test (APST), and autologous serum skin test (ASST) for autoimmune urticaria (AIU) diagnosis. This study was a case control study of 47 chronic spontaneous urticaria (CSU) patients and 47 healthy controls. Patients and control were subjected to ASST, APST, and ELISA assay of serum autoantibodies to FcεRIα. Histamine release assay (HRA) as the gold standard method for autoimmune urticaria diagnosis was performed after basophil percoll isolation and subjected to sera of both patients and control. The validity of ASST and autoantibodies to FcεRIα were determined in comparison to HRA. Autologous serum skin test was positive in 30 (63.8%) of CSU patients, and 12.7% of the healthy control (P=0.000). IgG autoantibodies to FcεRIα were demonstrated in 55.5% of the patients and were more common in patients with positive (80%) than negative ASST (11.7%) (P=0.000). There was significant positive correlation between "ASST" and "APST" positivity, and clinical severity as Spearman coefficient for this correlation was 0.477 (P=0.001). There was a significant association between IgG positivity to FcεRIα and disease severity as Spearman coefficient was 0.360 (P=0.02). Combined "ASST", "APST" and FcεRIα autoantibody tests revealed 100% sensitivity and 100% specificity for autoimmune urticaria diagnosis. In conclusion, combined anti-FcεRIα assay, with ASST, and APST improved the diagnosis of chronic autoimmune urticaria among patients with chronic spontaneous urticaria.