What is the largest antibody and the first involved in the primary immune response? Its function is to act as an antigenic receptor site on the surface of immature B-lymphocytes. It neutralizes toxins and contains 10 binding sites for antibody agglutination. It also contains 5 FC regions and is the most effective antibody for activating complement. What is this antibody called?
1) IgA
2) IgD
3) IgE
4) IgM