ANTIBODY-Types and Functions

To effectively fight the wide range of pathogens, the lymphocytes of the adaptive immune system have evolved to recognize a great variety of different antigens from bacteria, viruses, and other disease-causing organisms.

On B cells these proteins are the immunoglobulins (Ig), which these cells produce in a vast range of antigen specificities.
Membrane-bound form of immunoglobulin on the B-cell surface serves as the cell’s receptor for antigen, and is known as the B-cell receptor (BCR).
A secreted form of immunoglobulin of the same antigen specificity, is the antibody produced by terminally differentiated B cells—plasmablasts and plasma cells.
Characteristics of antibody isotypes is determined by
1. The number and location of interchain disulfide bonds
2. The number of attached oligosaccharide moieties.
3. The length of hinge region.
4. The number of C domain