Table 1.

IgA Involvement in Various Diseases.

Disease	Involvement of IgA
Autoimmune Disease [Section 5.1]	Selective IgA deficiency has a two-hit impact causing pathobiont expansion leading to dysbiosis and spontaneous gut inflammation [122,127] and unmitigated inflammation leading to autoimmune disease development [120].
Necrotizing Enterocolitis (NEC) [Section 5.2]	Dimeric IgA in mother’s milk helps to control the prevalence of Enterobacteriaceae providing a safeguard against NEC [151].
Inflammatory Bowel Diseases (IBD) [Section 5.3]	SIgA aids in preventing IBD pathogenesis by helping to facilitate microbiota stability [172], neutralization of procolitogenic fungi and bacteria via immune exclusion [103,180].
Colorectal Cancer (CRC) [Section 5.4]	IgA antibodies reactive to carcinoembryonic antigen to be cytotoxic to colonic tumor cells [196]. Promotes a proinflammatory tumor microenvironment for oncogenic growth [203].
Nephropathy & Vasculitis [Section 5.5]	IgA aggregates in the glomerulus of the kidney causing inflammation leading to nephropathy [198,199,200]. IgA deposits in the walls of the blood vessel leading to vasculitis [221].
Salmonella Infection [Section 5.6]	Promotes bacterial agglutination to become susceptible to immune exclusion or enchained growth by SigA for clearance [104,249,250].
Biliary Infection [Section 5.7]	SIgA is the predominant antibody in bile and helps to prevent primary and secondary hepatobiliary infection from intestinal or parasitic infection [258,265,266,267,268,269,270].