What distinguishes IgG antibodies from other types?

IgG antibodies are distinguished from other types of antibodies primarily by their prevalence in serum, where they account for about 75% of the total antibody level. This high concentration is significant because IgG plays a crucial role in the immune response, providing long-term protection against pathogens. It is effective in opsonization, neutralization, and activating complement pathways, making it vital for providing immunity after exposure to an antigen.

While other antibodies, such as IgE, are indeed involved in allergic responses, that characteristic does not apply to IgG specifically. IgM is typically the first antibody produced in response to an infection, further differentiating it from IgG. Other types of antibodies, like IgA, are predominantly found in mucosal areas, which is not a characteristic of IgG. Thus, the prominence of IgG in serum directly highlights its importance in the body's defense mechanisms, reinforcing the correct identification of its distinguishing feature in this context.