Mucosal surfaces in the gastrointestinal tract are continually exposed to native. commensal antigens and susceptible to foreign. infectious antigens. Immunoglobulin A (IgA) provides dual humoral responses that create a symbiotic environment for the resident gut microbiota and prevent the invasion of enteric pathogens. https://parisnaturalfoodes.shop/product-category/nutritional-yeast/