White, H. N. | Search bioRxiv

bioRxiv2025

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

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.

immunology↗

bioRxiv2018

Highly mutated memory cells drive an inefficient secondary antibody response to a variant protein

A powerful vaccine against mutable viruses might induce memory antibodies that either strongly bound antigenic variants or that could rapidly undergo secondary affinity maturation to achieve this. We have recently shown after secondary immunization of mice with a widely variant protein (Burton et al. 2018) that IgM+ memory B-cells with few mutations supported an efficient secondary germinal centre (GC) and serum response, superior to a primary response to the same protein. Here, boosting with more closely related proteins produced a GC response dominated by highly mutated B-cells that failed, not efficiently improving serum avidity even in the presence of extra adjuvant, and that was worse than a primary response. This supports a hypothesis that over certain antigenic differences, a cross reactive, mutated, memory B-cell compartment can be an impediment to affinity maturation.

immunology↗