CD22 and leukemia: Before treatment, the expression levels of CD19, CD20, and CD22 on the surface of leukemia cells were measured by flow cytometry in both groups (Rituximab group: CD19: 65.65%, CD20: 49.47%, CD22: 74.12%; Control group: CD19: 83.1%, CD20: 6.84%, CD22: 67.08%) (Fig. 1A).