Secretory IgA: The Mucosal Shield Being Systematically Dismantled Secretory IgA (sIgA) — the most abundant immunoglobulin in the human body — is a dimeric antibody produced by plasma cells in the lamina propria of mucosal tissues and secreted in vast quantities into the gut lumen, respiratory tract, urogenital tract, breast milk, and saliva, where it serves as the primary non-inflammatory immune defence against pathogen colonisation, toxin absorption, and antigen translocation. Unlike IgG-mediated responses that rely on complement activation and phagocytosis, sIgA works through 'immune exclusion' — binding to pathogens, food antigens, and toxic compounds at the mucosal surface and preventing their adherence and translocation across the epithelial barrier without triggering the inflammatory cascade. Chronic psychological stress, malnutrition, sleep deprivation, and dysbiosis all suppress sIgA secretion — creating the mucosal vulnerability through which environmental toxins, undigested food proteins, and microbial products gain access to the systemic immune system, initiating the sensitisation and inflammatory responses that manifest as food intolerances, allergies, and autoimmune conditions.
#secretory IgA #mucosal immunity
