IMMUNOLOGY

Detailed explanation-1: -Due to its large size, IgM is mostly intravascular and has a lower affinity for antigens. However, since pentameric IgM has 10 antigen binding sites, it has higher avidity (overall binding strength) for antigens than IgG and acts as an excellent activator of the complement system and agglutination.

Detailed explanation-2: -IgM is the first antibody built during an immune response. It is responsible for agglutination and cyto-lytic reactions since in theory, its pentameric structure gives it 10 free antigen-binding sites as well as it possesses a high avidity.

Detailed explanation-3: -Indeed, IgM is 100 to 10, 000 times more effective than IgG in mediating agglutination.

Detailed explanation-4: -As a consequence of its pentameric structure, IgM is a powerful agglutinating and precipitating antibody, a strong complement fixing immunoglobulin and thus is efficient in leading to the lysis of microorganisms. It is also involved in neutralization of toxins (Stahl and Sibrowski, 2003).