Citing this page: Lefranc, M.-P. et al., Dev. Comp. Immunol., 27, 55-77 (2003). PMID: 12477501

FR-IMGT lengths

Lengths of the FR-IMGT from human V-DOMAIN are according to the IMGT unique numbering for V-DOMAIN [1].

V-DOMAIN FR1-IMGT FR2-IMGT FR3-IMGT FR4-IMGT Total
VH 25 17 38 11 91
V-KAPPA 26 17 36 10 89
V-LAMBDA 25 17 36 (or 38 (1)) 10 88 (or 90 (1))

IMGT AA criteria for evaluation of immunogenecity

The lengths of the FR-IMGT are used for the IMGT evaluation of the immunogenicity of humanized variable domains [2]. Thus, the IMGT criteria include:

Number of different AA in FR/total FR-IMGT length

Humanized antibodies VH V-KAPPA
alemtuzumab 14/91 2/89
bevacizumab 23/91 7/89
trastuzumab 9/91 6/89

According to the IMGT® rules and IMGT Collier de Perles the number of different AA (or the numerator if expressed as a ratio) should be zero, or at least as close as possible of zero [2].

Trastuzumab

VH

3D Collier VH

V-KAPPA

3D Collier VH

For VH and V-KAPPA, the IMGT Colliers de Perles on 2 layers and the 3D structure representations are from 1n8z_H (IMGT/3Dstructure-DB).
3D structure representations are based on the IMGT Collier de Perles delimitations. The FR-IMGT, made of the 9 strands (arrows) and turns are in green, whereas the 3 CDR-IMGT are in red, orange and purple, respectively.
For amino acid changes with the closest germline V and J genes, see IMGT/DomainGapAlign results of VH 1n8z_H in IMGT/3Dstructure-DB.

IMGT notes:
(1) Lengths for IGLV5 and IGLV11 subgroups.
IMGT references:
[1] Lefranc, M.-P. et al., Dev. Comp. Immunol., 27, 55-77 (2003). PMID: 12477501 pdf with permission from Elsevier
[2] Magdelaine-Beuzelin, C. et al., Crit. Rev. Oncol. Hematol., 64, 210-225 (2007) PMID: 17624800
[3] Pommié, C. et al., J. Mol. Recognit., 17, 17-32 (2004). PMID: 14872534 pdf