A monoclonal antibody comprising an allotypic modification in the antibody heavy chain, wherein the antibody comprises a combination of heavy chains and light chains selected from the following possibilities (i) to (ix): (i) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 115 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 122, (ii) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 116 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 121, (iii) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 117 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 123, (iv) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 119 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 126, (v) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 118 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 125, (vi) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 120 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 124, (vii) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 120 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 127, (viii) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 120 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 128, and (ix) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 120 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 129; wherein said heavy chain comprises the amino acid sequences of SEQ ID NO: 46 and the allotypic modification is a replacement of K93R, D235E and L237M within the amino acid sequence of SEQ ID NO: 46. (i) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 115 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 122, (ii) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 116 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 121, (iii) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 117 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 123, (iv) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 119 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 126, (v) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 118 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 125, (vi) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 120 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 124, (vii) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 120 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 127, (viii) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 120 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 128, and (ix) the heavy chain comprises an amino acid sequence represented by SEQ ID NO: 120 and the light chain comprises an amino acid sequence represented by SEQ ID NO: 129;