Objectives: Disorders of humoral immunity in Takayasu's arteritis (TAK) have not been well explored. This study describes the characteristics of B cells and immunoglobulin (Ig) profile in patients with TAK.
Methods: Peripheral B cell populations assessed using flow cytometry and serum Ig levels assessed using a biochemical analyser in 98 newly diagnosed patients with TAK were analysed and compared with those of 31 patients with systemic lupus erythematosus (SLE) and 60 healthy controls (HCs). CD19+ B cell and IgG infiltration to the aortic tissue was evaluated by immunohistochemical staining.
Results: The proportion of peripheral CD3-CD19+ B cells and levels of serum IgG in TAK were lower than those in SLE, but higher than those in HCs. CD3-CD19+ B cell counts were higher in TAK than in HCs. Serum IgG and IgG1 levels were higher in active TAK than in non-active TAK. In TAK, positive correlations of serum IgG levels with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, Kerr score, and Indian Takayasu Clinical Activity Score (ITAS2010, ITAS-A) were observed before immunotherapy. After 6 months of immunotherapy, serum Ig levels significantly decreased. Positive correlations between the changes in IgG levels and values of ESR, CRP, Kerr score, and ITAS-A were detected. Immunohistochemical staining confirmed CD19+ B cell and IgG infiltration to the aortic wall in patients with TAK.
Conclusions: Enhanced B cells might contribute to the pathogenesis of TAK, and serum IgG levels could serve as a simple, useful biomarker to assess disease activity and monitor treatment response in TAK.