The effect of allergen immunotherapy on regulatory B cells in patients with allergic rhinitis

Allergic rhinitis (AR) is an IgE-mediated allergic inflammatory disease. Conventional pharmacotherapy and allergen-specific immunotherapy (AIT) is utilized for cure of AR. The mechanism of AIT hasn't been fully revealed. Regulatory T cells (Treg) contribution in immune tolerance is well known and regulatory B cell (Breg) subsets contribution in a number of diseases has just been revealed. Studies tried to establish a link between AIT and Bregs, however, still with lacking robust evidence. This study aimed to investigate Breg subsets in peripheral blood of AR patients following AIT. Breg subpopulations (CD19+CD73-CD25+CD71+, CD19+CD24h iCD27+ and CD19+CD24hi CD38hi ) were evaluated by flow cytometry in house dust mite (HDM) sensitized AR patients with an initial diagnose, AR patients following AIT of minimum 24 months and healthy individuals. In addition, dominance of regulatory T (Treg) cells known as Tr1 (CD3+CD4+ CD25+CD127-), which are already known to be stimulated following AIT were compared with that of Breg subsets. HDM specific IgG4 from sera samples were measured by Elisa. The induction of CD19+CD25+CD71+CD73- Breg cell subset in patients following AIT was reported, while the increased ratios of CD19+CD24hiCD27+ Breg subset was noted in AR patients prior to AIT. HDM specific IgG4 was induced following the course of AIT. The induction of CD19+CD25+CD71+CD73- Breg cell subset following AIT and increased levels of CD19+CD24hiCD27+ subset in AR patients could reveal differential contribution of Bregs in various stages of AR pathogenesis. Induction of IgG4 strongly supports the contribution of Bregs in success of AIT. Keywords: Allergic rhinitis, allergen, B regulatory cell, immunotherapy, immune regulation The present work was supported by the Research Fund of Istanbul University. Project no: 36719