Amino acid sequences of the IGK V-J-REGION and IGH V-D-J-REGION of Campath-1H [1] are displayed, according to the IMGT unique numbering for V-DOMAIN.

YTH34.5HL (CAMPATH-1G) is a Norway rat anti-CD52 antibody (IMGT/3Dstructure-DB 1bfo). Alemtuzumab (MABCAMPATH®, CAMPATH®) corresponds to the humanized antibody with HuVLCAMP kappa chains and HuVHCAMP mutant 2 heavy chains (IMGT/3Dstructure-DB 1ce1).

Humanization of the IGK V-J-REGION

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IGK V-J-REGION                                   FR1-IMGT           CDR1-IMGT       FR2-IMGT       CDR2-IMGT                   FR3-IMGT                    CDR3-IMGT    FR4-IMGT
                                                  (1-26)             (27-38)        (39-55)         (56-65)                    (66-104)                    (105-117)    (118-128)
                                              A             B           BC         C        C'        C'C"       C"         D           E          F          FG            G
                                           (1-15)        (16-26)     (27-38)    (39-46)   (47-55)   (56-65)    (66-74)   (75-84)     (85-96)    (97-104)   (105-117)    (118-128)
_____________________________________ _______________ ___________ ____________ ________ _________ __________ _________ __________ ____________ ________ _____________ ___________
                                      1       10   1516     23 26 27        38 3941   4647     5556       65 66     74 75   80 84 85  89    96 97   104 105 11112 117 118     128
                                      .........|....| |......|..| |..........| |.|....| |.......| |........| |.......| |....|...| |...|......| |......| |.....||....| |.........|
Noway rat YTH34.5HL (1bfo)     (1)    DIKMTQSPSFLSASV GDRVTLNCKAS QNI......DKY LNWYQQKL GESPKLLIY NT.......N NLQTGIP.S RFSGSG..SG TDFTLTISSLQP EDVATYFC LQHIS....RPRT FGTGTKLELK
Human     Rei                  (2)    DIQMTQSPSSLSASV GDRVTITCQAS QDI......IKY LNWYQQKP GKAPKLLIY EA.......S NLQAGVP.S RFSGSG..SG TDFTFTISSLQP EDIATYYC QQYQS....LPYT FGQGTKVEIK
Humanized HuVLCAMP  (1ce1)            DIQMTQSPSSLSASV GDRVTITCKAS QNI......DKY LNWYQQKP GKAPKLLIY NT.......N NLQTGVP.S RFSGSG..SG TDFTFTISSLQP EDIATYYC LQHIS....RPRT FGQGTKVEIK

Humanization of the IGH V-D-J-REGION

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IGH V-D-J-REGION                                 FR1-IMGT           CDR1-IMGT        FR2-IMGT      CDR2-IMGT                   FR3-IMGT                    CDR3-IMGT    FR4-IMGT
                                                  (1-26)             (27-38)         (39-55)        (56-65)                    (66-104)                    (105-117)    (118-128)
                                              A             B           BC         C        C'        C'C"       C"         D           E          F          FG            G
                                           (1-15)        (16-26)     (27-38)    (39-46)   (47-55)   (56-65)    (66-74)   (75-84)     (85-96)    (97-104)   (105-117)    (118-128)
_____________________________________ _______________ ___________ ____________ ________ _________ __________ _________ __________ ____________ ________ _____________ ___________
                                      1       10   1516     23 26 27        38 3941   4647     5556       65 66     74 75   80 84 85  89    96 97   104 105 11112 117 118     128
                                      .........|....| |......|..| |..........| |.|....| |.......| |........| |.......| |....|...| |...|......| |......| |.....||....| |.........|
Norway rat YTH 34.5HL (1bfo)     (3)  EVKLLESGG.GLVQP GGSMRLSCAGS GFTF....TDFY MNWIRQPA GKAPEWLGF IRDKAKGYTT EYNPSVK.G RFTISRDNTQ NMLYLQMNTLRA EDTATYYC AREGHT.AAPFDY WGQGVMVTVSS
Human      Newm                  (4)  QVQLQESGP.GLVRP SQTLSLTCTVS GSTF....SNDY YTWVRQPP GRGLEWIGY VFYH...GTS DDTTPLR.S RVTMLVDTSK NQFSLRLSSVTA ADTAVYYC ARNLIA..GCIDV WGQGSLVTVSS
Humanized  HuVHCAMP mutant 1          QVQLQESGP.GLVRP SQTLSLTCTVS GFTF....SDFY MNWVRQPP GRGLEWIGF IRDKAKGYTT EYNPSVK.G RVTMLVDTSK NQFSLRLSSVTA ADTAVYYC AREGHT.AAPFDY WGQGSLVTVSS
Humanized  HuVHCAMP mutant 2 (1ce1)   QVQLQESGP.GLVRP SQTLSLTCTVS GFTF....TDFY MNWVRQPP GRGLEWIGF IRDKAKGYTT EYNPSVK.G RVTMLVDTSK NQFSLRLSSVTA ADTAVYYC AREGHT.AAPFDY WGQGSLVTVSS

Legend:
In blue, conservation of amino acids from YHT34.5HL in the reshaped antibodies in order to restore the hydrophobic core formed by residues 28, 35, and 39 [2]. The first mutation S28>F regains the prior affinity of CAMPATH-1H for CD52. The second mutation S35>T ensures CAMPATH-1H to retain the highly specific and tight binding characteristic of the rat antibody.

The humanization of CAMPATH-1H was made by using the Kabat CDR (green) and FR (red) delimitations.
Interestingly, the analysis using the IMGT unique numbering [3, 4, 5] shows that:

  1. The two necessary amino acid changes, S28>F and S35>T, are in the CDR1-IMGT. These positions were previously considered as Kabat FR1.
    According to the IMGT unique numbering, positions 27 to 38 should have come from the 'rat' sequences, therefore preserving the specificity.
  2. The positions 66 to 78 belong to the FR3-IMGT (C" strand). These positions were previously considered as Kabat CDR2.
    According to the IMGT unique numbering, positions 66 to 78 could have been kept from the 'human' sequences, therefore reducing the immunogenicity.

IMGT notes:
(1) The IGK V-J YTH34.5HL rearrangement is the following: IGKV22S7*01-IGKJ2-3*01.
(2) The IGK V-J Rei rearrangement is the following: IGKV1-33*01 (or IGKV1D-33*01)-IGKJ2*01, as identified by IMGT curators (M. Ruiz, O. Posukh and M.-P. Lefranc).
(3) The IGH V-D-J YTH34.5HL rearrangement is the following: IGHV7S6*01-IGHJ2*01.
(4) The probable IGH V-D-J Newm rearrangement is the following: IGHV4-59*01-IGHJ3*01, as identified by IMGT curators (F. Bellahcene and M.-P. Lefranc), using IMGT/DomainGapAlign.
References:
[1] Riechmann, L. et al., Nature, 332, 323-327 (1988). PMID: 3127726
[2] Cheetham, G. M. T. et al., J. Mol. Biol., 284, 85-99 (1998). PMID: 9811544
[3] Lefranc, M.-P., Immunology Today, 18, 509 (1997). PMID: 9386342 LIGM:194 pdf
[4] Lefranc, M.-P., The Immunologist, 7, 132-136 (1999). LIGM: 217 pdf
[5] Lefranc, M.-P. et al., Dev. Comp. Immunol., 27, 55-77 (2003). PMID: 12477501 LIGM:268 pdf