Background B lymphocytes are involved in the pathogenesis of AAVs by the production of cytokines/chemokines and autoantibodies. Immunosuppressive therapy is effective in AAVs but may lead to a decline in serum immunoglobulin (Ig) concentrations and to changes in the peripheral B cell compartment.
Objectives To assess the effect of immunosuppressive treatment on the peripheral B cell compartment in AAV patients.
Methods In 36 AAV patients a retrospective analysis of Ig concentrations and flowcytometry of peripheral B-cells was conducted. A group of 26 healthy donors served as control.
Results 33 of 36 AAV patients were treated with cyclophosphamide (CYC) prior to analysis (median cumulative dose 14.5g; IQR 5.825-30). At the time of analysis 29 patients were treated with prednisone (median dose 5mg/d; IQR 3.75-8.75), eight received methotrexate (MTX), six azathioprine (AZA), six leflunomide (LEF), four mycophenolate mofetile, and eleven patients had no DMARD. Decreased IgG serum concentrations (<7g/L) were detected in 14 patients. Compared to healthy controls absolute cell counts and relative percentages of lymphocytes and CD19+ B cells were significantly decreased in AAV patients (Table 1). Notably, IgD+CD27+ marginal zone B cells were significantly decreased in AAV patients both in absolute cell counts and relative percentages. IgD+CD27- naive B cells, IgD-CD27+ memory B cells, IgA+ B cells, transitional B cells and plasmablasts were significantly decreased in absolute numbers but not in relative percentages. In the subgroup of AZA treated patients absolute numbers of all B cell subpopulations except for IgA+ B cells and plasmablasts were reduced. In LEF treated patients only IgD+CD27+ B cells were reduced. In MTX-treated patients only IgD+CD27+ B cells were reduced both in absolute numbers and percentage while IgD+CD27- and IgD-CD27+ B cells, IgA+ B cells and plasmablasts were decreased only in absolute numbers.
Conclusions Immunosuppressive therapy leads to a decrease in absolute numbers of CD19+ B cells and all examined B cell subpopulations, while IgD+ CD27+ MZ-like B cells showed also a relative decrease.
Disclosure of Interest None Declared
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