mhc writes "This article relates interesting differences between the VH CDR3 repertoires of mouse and human. A full analysis was performed of the complete Kabat and IMGT antibody databases to arrive at these conclusions. Among them: that compared to the human sequence, the mouse CDR3 is shorter, more hydrophilic, enriched in tyrosine, and less likely to be structurally constrained by proline or intrachain cys-cys bonding. The functional inference is that the mouse repertoire recognizes the antigen universe in a different manner than human, and that the human response can achieve a much greater divergence than does the mouse. The authors suggest that this analysis can serve as a benchmark by which antigen-specific responses can be compared (e.g. is an anti-DNA response more hydrophilic than the universe of anti-self autoantibody responses, or just more hydrophilic than the "average" response as determined from this analysis?)
Zemlin M, Klinger M, Link J, Zemlin C, Bauer K, Engler JA, Schroeder HW Jr, Kirkham PM. "Expressed murine and human CDR-H3 intervals of equal length exhibit distinct repertoires that differ in their amino acid composition and predicted range of structures." J Mol Biol. 2003 Dec 5;334(4):733-49
(ed.) VH CDR3 = variable heavy (chain immunoglobulin) complement determining region 3. (Originally posted on MedDot.org January 6, 2005)
Tuesday, August 22, 2006
Immunity: Statistically different functional CDR3s in mouse
at 2:30 PM
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If, then, maybe...
CDR3 is a major contributor to the binding site, suggesting that the antibody binding site is smaller in mice than humans. It seems that a smaller antigen combining site should make a difference in the ability of the immune system, or B cells anyway, to recognize pathogens or discriminate self from foreign epitopes. However, there may be enough layers of control to obscure any effect, e.g., compensitory changes in T cell specificity.
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