Which immunoglobulin is most common in serum and responsible for long-term immunity?

Immunoglobulin G (IgG) is the most abundant antibody found in serum and plays a crucial role in long-term immunity. It constitutes about 75-80% of the immunoglobulin pool in the bloodstream. The primary function of IgG is to provide the body with adaptive immunity against pathogens, as it can recognize and neutralize toxins, viruses, and bacteria. Additionally, IgG has the ability to cross the placenta, providing passive immunity to the fetus during pregnancy, which is vital for the newborn’s early defense against infections.

IgG is produced in significant quantities after initial exposure to an antigen, forming the bulk of the secondary immune response. This means that after the first encounter with a pathogen, memory B cells retain the information about that pathogen and will produce IgG upon subsequent exposures, allowing for a robust and rapid immune response. This long-lasting presence in the body ensures that an individual is better prepared against reinfection.

In contrast, other immunoglobulins listed have different roles: IgA is primarily found in mucosal areas and secretions like saliva and tears, IgE is involved in allergic responses and protection against parasitic infections, and IgM is the first antibody produced in response to an infection but does not provide long