What do the subclasses of IgA do?

IgA1

IgA1 is the predominant subclass in serum, accounting for about 85% of the total IgA concentration. IgA1 exhibits a strong immune response to protein antigens and a moderate response to lipopolysaccharides and polysaccharides. Although IgA1 is broadly resistant to many proteases, some can target and cleave the hinge region.

IgA2

IgA2 represents only up to 15% of total IgA in serum, but it is found in higher percentages in secretions. IgA2 plays a critical role in fighting against polysaccharide and lipopolysaccharide antigens in the mucosa of the eyes, airways, and gastrointestinal tract. It is strongly resistant to proteolysis and several bacterial proteases, underscoring its importance in fighting bacterial infections.