Why is IgG the most abundant antibody?

IgG is the most abundant antibody in the bloodstream because it plays a crucial role in the immune response, providing long-term protection against pathogens. Its structure allows for effective binding to antigens and facilitates opsonization, neutralization, and activation of complement pathways. Additionally, IgG can cross the placenta, providing passive immunity to the fetus. Its ability to persist in circulation and its diverse functions make it essential for maintaining immune defense.