The<unk>  immune system provides three main functions: *Serving as the body's first line of defense from harmful antigenic structures and infection. *Preventing systemic immune responses to commensal bacteria and food antigens. *Regulating appropriate immune responses to pathogens encountered on a daily basis.
Mucosal immunology
Gastrointestinal physiology
Immunology
Sensation 
Immune system
Cancer immunology
Cognition
Biochemistry