Which immunoglobulin class accounts for the majority of antibodies in serum?

IgG is the most abundant immunoglobulin class in serum, comprising approximately 70-75% of the total serum antibodies. It plays a crucial role in the immune response, providing long-term protection against pathogens. IgG is known for its ability to opsonize pathogens, neutralize toxins, and activate complement, allowing it to enhance phagocytosis and contribute to the elimination of infections.

In contrast, IgA is primarily found in mucosal areas and secretions, such as saliva and tears, accounting for about 15-20% of serum antibodies. IgE, while important for mediating allergic reactions and responses to parasitic infections, is present in very low concentrations in serum, typically less than 1%. IgM is the first antibody produced during an initial immune response and constitutes about 5-10% of serum antibodies, making it less prevalent than IgG overall.

Understanding the distribution and function of different immunoglobulin classes is critical for comprehending the immune system's dynamics and the body's defense mechanisms.