Immunoglobulin A and the microbiome
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Updated: Dec 9, 2025

Murine Nasal Lavage Fluid Collection without Blood Contamination
Published on: July 11, 2025
1Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA.
Abstract:
The trillions of microbes that constitutively colonize the intestine (the gut microbiota) impact diverse aspects of human physiology in health and disease. Immunoglobulin A (IgA) is the most abundant antibody isotype produced at mucosal surfaces, and nearly two grams of IgA is secreted into the intestine every day. Secretory IgA (SIgA) provides critical protection against pathogens and toxins, but can also directly bind to and 'coat' commensal bacteria in the gut. Commensal targeting by SIgA shapes gut microbiota composition, modulates bacterial behaviors, and enforces host-microbiota homeostasis in both mice and humans.
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