Effects of rituximab on VH1-69 clonal B cells. (A) Flow cytometry figures of a patient with HCV-MC vasculitis demonstrating staining with anti–Vh1-69 gene product mAb (MC pre-Rx) and disappearance of VH1-69⁺ B cells following rituximab (MC post-Rx). (B) Histogram representing the percentage of VH1-69⁺ cells among CD19⁺ B cells (mean ± SEM) in patients with HCV-MC vasculitis (n = 11) before (MC pre-Rx) and after (MC post-Rx) rituximab.