Cd22 Gating For Flow Cytometric Analysis In Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia After Cd19 Car-T Therapy

CD19 has been as a classic marker for gating B-cells in flow cytometric analysis. However, with the application of CD19 chimeric antigen receptor (CAR) T-cell therapy for treating relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL), CD19 gating is no longer adequate for B-ALL patients post CD19 CAR-T therapy owing to CD19 antigen loss, under this circumstance, cytoplasmic CD79a (cCD79a) emerged to replace CD19 as a gating marker of B-cells. Nevertheless, cCD79a was intracellular staining and time consuming, sometimes with unspecific stain or without enough cells for analysis after permeabilization and extra washing. CD22 is another pan B marker expressed on the surface of B lymphocytes at different stages, could be as alternative choice of B-cell identification after CD19 CAR-T. Here, we evaluated the possibility of CD22 as a B-cell gating marker by comparing the expression of CD22 and cCD79a in CD19 negative relapsed B-ALL patients.