Humanized cd19 antibody and use thereof

A humanized antibody or antigen-binding fragment specifically binding to CD19, wherein the humanized antibody or the antigen-binding fragment comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises:

• a. a CDR1 comprising an HCDR1 of a VH set forth in any one of SEQ ID NOs:
• 8-10;
• b. a CDR2 comprising an HCDR2 of a VH set forth in any one of SEQ ID NOs:
• 8-10;
• c. a CDR3 comprising an HCDR3 of a VH set forth in any one of SEQ ID NOs:
• 8-10;
• and
• d. framework regions comprising framework regions HFR1, HFR2, and HFR3 of IGHV2-26*01 set forth in SEQ ID NO:
• 3, and a framework region HFR4 of IGHJ6*01 set forth in SEQ ID NO:
• 4;
• and according to numbers of the Kabat numbering scheme, the framework regions of heavy chain variable region further comprising two mutations:
• Q1E, R94K;
• and
• the light chain variable region comprises:
• a. a CDR1 comprising an LCDR1 of a VL set forth in SEQ ID NO:
• 7;
• b. a CDR2 comprising an LCDR2 of a VL set forth in SEQ ID NO:
• 7;
• c. a CDR3 comprising an LCDR3 of a VL set forth in SEQ ID NO:
• 7;
• and
• d. framework regions comprising framework regions LFR1, LFR2, and LFR3 of IGKV1-39*01 set forth in SEQ ID NO:
• 5, and a framework region LFR4 of IGKJ4*01 set forth in SEQ ID NO:
• 6;
• and according to numbers of the Kabat numbering scheme, the framework regions of light chain variable region further comprising three mutations:
• K42G, P44V□F71Y.