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Mouse IgA （Immunoglobulin A） is a key antibody isotype that plays a critical role in mucosal immunity. It is predominantly found in mucosal surfaces such as the intestines, respiratory tract, and urogenital tract, where it serves as the first line of defense against pathogens. Mouse IgA exists in two forms: monomeric IgA in the serum and dimeric or polymeric IgA in mucosal secretions. The latter is often associated with a secretory component （SC） and a joining （J） chain, which facilitate its transport across epithelial cells and enhance its stability in mucosal environments. Mouse IgA functions by neutralizing pathogens, preventing their adhesion to epithelial cells, and promoting their clearance through mechanisms such as immune exclusion. It also plays a role in maintaining homeostasis with commensal microbiota. Due to its importance in mucosal immunity, mouse IgA is widely studied in research related to infections, allergies, and inflammatory diseases.