Increased Circulating FceRII-Bearing B-Lymphocytes and Serum Levels of IL-4 In Non - Autoreactive Chronic Idiopathic Urticaria

¹Roshdy Wasfi Mohamed, ²Amal Fathy, ³Abeer Ezzat El-sayed

Departments of ¹Dermatology & Andrology, ²Clinical Pathology and ³Microbiology & Immunology, Suez Canal University, Ismailia, Egypt

The exact pathophysiology of chronic idiopathic urticaria (CIU) is not well understood. The concept of autoreactivity has evolved to explain the disease in up to 50 % of cases, while the search for other mechanisms is still needed to explain the disease, at least among the remaining subpopulation of non-autoreactive CIU. Therefore, we thought to investigate some aspects of the IgE-dependent, lymphocyte-mediated late-phase response (LPR) of anaphylaxis. We searched for percentages of FceRII-bearing (CD23⁺) B and T lymphocytes and correlated this with total IgE serum levels, IL-4 serum levels and the disease severity scores. Twenty-five patients with non-autoreactive CIU and ten healthy control subjects participated in this study. CD23⁺ B- and T-cells were assessed by flow cytometry, total IgE serum levels were estimated by enzyme linked fluorescent assay (ELFA), IL-4 serum levels were estimated by Enzyme Amplified Sensitivity Immunoassay (EASIA), while disease severity was determined by a daily self-assessment urticaria activity and itching score. Our results showed that the mean values for percentages of CD23⁺ B-cells (6.7±2.3%), total IgE serum levels (139.6±103.9mg/dl) and IL-4 serum levels (18.3±14.7ng/ml) for patients were statistically significant (p=0.002, 0.013 and 0.008, respectively), when compared with the corresponding values for controls (4.0 ±1.7%, 51.5±25.1mg/dl, and 5.1±4.1ng/ml, respectively), while the difference between the mean percentage of CD23⁺ T-cells for patients (2.8±2%) and that for controls (2.1±0.6%) was non-significant (p=0.267). Strong positive correlations were detected between percentages of CD23⁺ B-cells and severity scores (r= 0.678, p= 0.0001), total IgE serum levels (r= 0.756, p= 0.0001) and IL-4 serum levels (r= 0.709, p= 0.0001), while no correlation was detected between CD23⁺ B-cells and CD23⁺ T-cells (r= 0.188, p= 0.368). It is concluded, that CD23⁺ B-cells, regulated by IL-4, may contribute in the pathogenesis of non-autoreactive CIU, by producing high levels of IgE and possibly lymphokines, while CD23⁺ T-cells may be involved in early antigen recognition. This may have a future therapeutic ramification in this distinct subset of CIU by targeting low-affinity IgE receptors.