Abnormalities in peripheral cell homeostasis of HCV-MC vasculitis revert following rituximab. Naive (IgD⁺CD27⁻CD38^low) lymphopenia (A), expansion of memory (IgD⁻CD27⁺CD38^low) B cells (B) and plasmablasts (IgD⁻CD27^highCD38^high) (C), and quantitative deficiency of regulatory T cells CD4⁺CD25⁺FoxP3⁺ (D) in patients with mixed cryoglobulinemia (MC) vasculitis (MC pre-Rx) (n = 21) compared with healthy volunteers (Ctrls) (n = 15) and chronic HCV patients without MC-vasculitis (HCV Ctrls) (n = 20). Improvement of peripheral B- and T-cell abnormalities after rituximab in patients with MC vasculitis (MC post-Rx). Data are expressed as mean plus or minus SEM.