Which among the following immunoglobulin predominates in the circulation and persists for many years after exposure ?

IgG predominates in the circulation and persists for many years after exposure. IgM is the earliest specific antibody to appear in response to infection. Secretory IgA is impoant in immunity at mucosal surfaces, while monomeric IgA appears in the serum. IgE is impoant in allergic and parasitic diseases. Ref: Harrison's Principles of Internal Medicine, 18e, Chapter 119.Introduction to Infectious Diseases.