What is Food-Specific Immunoglobulin A?
Secretory IgA is the dominant immunoglobulin at mucosal surfaces, synthesised locally by plasma cells in the lamina propria of the gut and transported across the epithelium as a dimeric molecule bound to secretory component. It neutralises luminal antigens, modulates microbial colonisation, and participates in immune exclusion without activating complement or triggering inflammation. Serum IgA — a mix of monomeric and polymeric forms — reflects both mucosal spillover and systemic production; its titre against food antigens is proposed as a marker of repetitive mucosal exposure and loss of oral tolerance, though this interpretation remains contested.