The adaptive immunity
- Mediated by proteins called antibodies or immunoglobulins (Igs).
- Binding of antigen to the Fab antigen-binding region unmasks the binding sites on the Fc portion which mediates the functions of the antibody.
- Antibodies work in four main ways:
- Neutralize the biological activity of a vital microbial molecule, e.g. a binding protein or toxin.
- Target microbes for phagocytosis.
- Activate complement.
- Activate cytotoxic immune cells.
- Antibody production is initiated following binding of an antigen to its specific B-cell receptor on the surface of naïve B-lymphocytes in the presence of an additional signal from CD4+ helper T-lymphocytes.
