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Antibody repertoire development in the sheep.
Craig N Jenne1, Laurie J Kennedy, John D Reynolds
1Department of Cell Biology and Anatomy, Immunology Research Group, University of Calgary, 3330 Hospital Dr. N.W., Calgary, Alta., Canada.
Developmental and Comparative Immunology
|August 9, 2005
Summary
Sheep immunoglobulin (Ig) diversification involves fewer gene segments but relies on critical somatic hypermutation for B cell survival. This process is essential for developing the primary Ig repertoire, with B cells undergoing apoptosis if mutation fails.
Area of Science:
- Immunology
- Molecular Biology
- Veterinary Science
Background:
- The model for sheep immunoglobulin (Ig) repertoire diversification has recently undergone significant revision.
- Previously, it was believed to involve limited V(D)J gene segment rearrangement followed by extensive antigen-independent somatic hypermutation.
Purpose of the Study:
- To update the understanding of immunoglobulin repertoire diversification in sheep.
- To highlight the critical role of somatic hypermutation in B cell development and survival.
Main Methods:
- Review of recent studies on sheep Ig repertoire diversification.
- Analysis of B cell development pathways, including V(D)J rearrangement and somatic hypermutation.
- Investigation of B cell apoptosis in relation to mutation status.
Main Results:
- Sheep Ig diversification is less recombinatorially restrictive and involves fewer mutational events than previously thought.
- Somatic hypermutation, though occurring at lower rates, remains critical for primary Ig repertoire development.
- B cells failing to undergo somatic hypermutation undergo apoptosis, indicating its essential role in selection.
Conclusions:
- The ileal Peyer's patch is a major site for B cell proliferation, selection, and Ig diversification via somatic hypermutation, despite likely lacking de novo V(D)J rearrangement.
- Somatic hypermutation is a key driver of B cell survival and Ig repertoire development in sheep.