How many types are there of IgA?

How many types are there of IgA?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

IgA exists in two subclasses in humans: IgA1 and IgA2. These two differ in hinge region length and tissue distribution. IgA1 has a longer hinge region, is the predominant form in serum, and is more susceptible to proteolysis. IgA2 has a shorter hinge, is more resistant to proteases, and is more common in secretions at mucosal surfaces, especially in the colon. When IgA is secreted into mucosal areas, it often forms secretory IgA as a dimer joined by a J chain, which helps stability in the harsh mucosal environment. Since there are two distinct subclasses, there are two types of IgA.

IgA exists in two subclasses in humans: IgA1 and IgA2. These two differ in hinge region length and tissue distribution. IgA1 has a longer hinge region, is the predominant form in serum, and is more susceptible to proteolysis. IgA2 has a shorter hinge, is more resistant to proteases, and is more common in secretions at mucosal surfaces, especially in the colon. When IgA is secreted into mucosal areas, it often forms secretory IgA as a dimer joined by a J chain, which helps stability in the harsh mucosal environment. Since there are two distinct subclasses, there are two types of IgA.