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bioRxiv · 10.1101/2025.04.07.647564

VH-replacement shapes the antibody repertoire by targeting non-pairing heavy-chains

White, H. N.·Chovanec, P.·Biggins, L.·French, E. C.·Bullen, G.·Andrews, S.·Corcoran, A. E.
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Abstract

The diversity of antibodies underpins robust immune responses. During the formation of the antibody repertoire in early bone marrow B-cells, random antibody heavy-chain proteins are generated from recombined V, D and J gene-segments. Many are non- functional and are negatively selected. Critically, this phase of development is impacted by ageing and inflammation. To understand this process in normal mice we have undertaken the first in-depth analysis of heavy-chain selection at this pre-B cell transition. We find independent selection acting on three regions of the CDR3 antigen binding site, with particularly heavy counter-selection of certain productive VH/JH combinations. This led us to hypothesise that VH-replacement is targeting productive VDJ rearrangements that cannot pair with the surrogate light-chain (SLC). We detect VH-replacement recombination products that closely follow the pattern of counter- selection of productive VDJ. This reveals a physiological role for VH-replacement: the developmental release of B-cells that are stalled, with a productive but not SLC-pairing VDJ, leading to re-modelling of the early VDJ repertoire toward locus-distal VH that we show are more tolerant of CDR3 composition.

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White, H. N., Chovanec, P., Biggins, L., French, E. C., Bullen, G., Andrews, S., Corcoran, A. E.. 2025-04-11. VH-replacement shapes the antibody repertoire by targeting non-pairing heavy-chains. https://doi.org/10.1101/2025.04.07.647564

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