Persistent Off-Season Dysregulation of Memory B Cell Subsets in Allergic Rhinitis

Allergic rhinitis (AR) is a common allergic airway disease. Although B cells play essential roles in AR pathogenesis, their subset distribution outside the allergen exposure period remains poorly characterized.

To profile peripheral blood B cell subsets in AR patients during the pollen-free season and compare them with healthy controls (HC), aiming to identify persistent immunological alterations and potential biomarkers.

Peripheral blood mononuclear cells (PBMCs) were collected from a total of 28 participants, 14 patients with allergic rhinitis (AR) and 14 healthy controls (HC) during the off-season. B cell subsets were identified using flow cytometry based on IgD and CD27 expression, classifying cells as naïve (IgD⁺CD27^-), unswitched memory (IgD⁺CD27⁺), switched/conventional memory (IgD^-CD27⁺), and unconventional memory B cells (IgD^-CD27^-). CD38 and CD24 were utilized to further distinguish transitional, naïve, memory, and plasma cell phenotypes. Immunoglobulin isotypes (IgG1-4, IgA1⁺/IgA2⁺) were assessed specifically within conventional memory B cells, while CD86 expression was evaluated on IgM⁺ memory-like and naïve B cells. Additionally, kappa (κ) and lambda (λ) light chain usage was analyzed to assess light chain distribution.

AR patients displayed lower frequencies of IgG1⁺, IgG2⁺, and IgA1⁺/IgA2⁺ memory B cells, along with elevated frequencies of IgG4⁺ and κ⁺ B cells. Additionally, CD86⁺IgM⁺ memory-like B cells were significantly reduced in AR, suggesting altered activation dynamics. No significant differences were observed in CD24/CD38 profiling.

Even outside allergen exposure, AR patients exhibit systemic B cell dysregulation, characterized by skewed class switching, altered subset distribution, and reduced activation markers expression. These findings underscore persistent immune imbalance in AR, identify potential off-season biomarkers of allergic inflammation.