In: Anatomy and Physiology
What are the major immunoglobulins and their function?
There are 5 major immunoglobulins. They are:
1.IgM - Membrane bound immunoglobulin on the surface of immature and mature B cells. It is the first antibody produced in a primary response to an Antigen and also first antibody produced by the fetus. It is efficient in binding antigens with many repeating epitopes such as viruses. It is for classical complement activation.
2. IgD - Membrane bound immunoglobulin on the surface of mature Bcells. No biological effector function known.
3.IgA- Found in gastrointestinal, Respiratory and urogenital tract mucosa.Predominant antibody class in secretions ( saliva,tears,breast milk and mucosa). It is the first line of defence against Infection by microorganisms.
4. IgG- Most abundant class with 4 isotypes- IgG1,IgG2, IgG3,IgG4. It crosses placenta. It is for opsonization and for acquired immunity.
5. IgE - Defence against parasite infections. Associated with hypersensitivity reactions, found mainly in tissues. It's interaction with basophils and mastocytes causes histamine release.