Which antibody class is predominant in human serum?

The predominant antibody class in human serum is IgG. This immunoglobulin plays a crucial role in the immune response, being responsible for the majority of antibody-based immunity against invading pathogens. IgG accounts for approximately 70-75% of the total immunoglobulin pool in serum, making it the most abundant antibody.

One of the key functions of IgG is its ability to neutralize toxins and viruses, opsonize pathogens for phagocytosis, and activate the complement system. It circulates in the bloodstream and is capable of crossing the placenta, providing maternal immunity to the fetus. This unique ability also enhances the infant's initial defense against infections in early life.

Other antibody classes like IgM, IgA, and IgE have distinct roles in the immune response but are present in lower concentrations within serum. IgM is the first antibody produced during an infection and is crucial for initial immune responses. IgA primarily functions in mucosal immunity, protecting surfaces like the respiratory and gastrointestinal tract. IgE is associated primarily with allergic reactions and responses to parasitic infections.

Understanding IgG's predominant presence and function helps clarify the specific roles of each antibody class within the larger context of the immune system, highlighting why IgG is so vital to