What is the Difference Between IGA and IGG?

Immunoglobulin A (IgA) and Immunoglobulin G (IgG) are two types of antibodies that play crucial roles in the immune system. They differ in their distribution, function, and subclasses. Here are the main differences between IgA and IgG:

Distribution: IgA is primarily found in the linings of the respiratory tract and digestive system, as well as in saliva, tears, and breast milk. In contrast, IgG is the most common antibody and is found in blood and other body fluids, protecting against bacterial and viral infections.
Function: IgA is involved in the immune response in mucosal surfaces, while IgG is involved in a wide range of immune responses, including providing the majority of humoral immunity. IgA is a less potent opsonin and a weak activator of the complement system, while IgG efficiently opsonizes pathogens for engulfment by phagocytes and activates the complement system.
Subclasses: IgA has two subclasses, IgA1 and IgA2, while IgG has four subclasses: IgG1, IgG2, IgG3, and IgG4. These subclasses have different functions and levels of effectiveness in the immune response.
Production: Although IgG is the most common class of immunoglobulin, more IgA is synthesized by the body daily than any other class of antibody. However, IgA is not as stable as IgG, and therefore, it is present in lower amounts at any given time.

In summary, IgA and IgG are two types of antibodies with distinct functions, distributions, and subclasses. IgA is mainly found in mucosal surfaces and plays a role in immune responses in those areas, while IgG is the most common antibody and is involved in a wide range of immune responses, including providing the majority of humoral immunity.