Natural antibody repertoire from microbial glycan

The gut microbial glycan landscape is rewritten across three nested timescales (clonal phase variation, mucosal remodeling, and horizontal gene transfer), so no fixed antigenic target persists.

Microbial glycan exposure instructs humoral immunity at three separable levels: the magnitude of the response, which germline B-cell clones are recruited, and the specificity of the mature repertoire.

The natural antiglycan antibody repertoire is not a fixed inheritance but a developmental transcript, founded by the microbes an individual first meets and revised thereafter by diet, infection, vaccination, and inflammation.

Whether an antiglycan response protects or injures turns on antigen identity, tissue accessibility, Fc glycoform, and inflammatory context, not on isotype alone; the same anti-Saccharomyces cerevisiae antibodies specificity is benign or pathogenic depending on Fc galactosylation.
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https://www.cell.com/trends/microbiology/fulltext/S0966-842X(26)00302-1
https://sciencemission.com/microbial-glycan