Immunoglobulin A (IgA)

Immunoglobulin A (IgA) is a type of antibody that plays a crucial role in the immune system by protecting mucous membranes in areas like the mouth, gut, respiratory passages, and urogenital tract. It helps prevent infections by neutralizing bacteria, viruses, and toxins at these entry points. IgA is found mainly in secretions such as saliva, tears, and mucus, forming a first line of defense that stops harmful pathogens from entering the body. It also exists in the bloodstream but is most important in mucosal immunity, maintaining the body's barrier against infection.