There is provided an anti-human IL-21 monoclonal antibody comprising: (a) a heavy chain region comprising: (i) a heavy chain variable region CDR1 comprising SEQ ID NO: 63； (ii) a heavy chain variable region CDR2 comprising SEQ ID NO: 65； and (iii) a heavy chain variable region CDR3 comprising SEQ ID NO: 67； and (b) a light chain region comprising: (i) a light chain variable region CDR1 comprising SEQ ID NO: 71； (ii) a light chain variable region CDR2 comprising SEQ ID NO: 73； and (iii) a light chain variable region CDR3 comprising SEQ ID NO: 75. There is also provided a hybridoma designated 366.328.10, wherein the hybridoma is deposited with the American Type Culture Collection having the ATCC Patent Deposit Designation PTA-8789.
