Antibody Production

AnTIBODy PRODuCTIOn Antigens Clonal Selection All organisms have unique molecules on the surface of cells • Molecules that trigger immune responses are antigens Immune systems must be challenged with specific antigens in order to initiate an appropriate response (antibody production) • Macrophages present antigen fragments to TH cells • TH cells activate antigen-specific B cells (clonal selection) • The B cells divide and differentiate into plasma cells that produce large quantities of specific antibodies • A small proportion differentiate into B memory cells Antigens act to trigger the production of specific antibodies • E.g. Antigens on red blood cells will stimulate antibody production in a person with a different blood group Antibodies Clonal Selection Antibodies aid in pathogen destruction by promoting: • Phagocyte recruitment • Agglutination • Neutralization • Inflammation • Complement activation Antibodies Plasma Cells Memory B Cell Immunological Memory Types of Immunity The adaptive immune response includes the production of memory cells following an initial pathogenic infection • Memory cells persist for years, secreting antibodies • If re-infection with the same antigen occurs, memory cells can respond faster and with much greater potency • As a result, disease symptoms do not develop (immunity) Immunity can be active (able to produce own antibodies): • Natural active immunity = normal response to infection • Artificial active immunity = immunity via vaccination Immunity can be passive (acquires antibodies externally): • Natural passive immunity = via breastfeeding • Artificial passive immunity = monoclonal antibodies Antibody Levels 100 Monoclonal Antibodies 10 2nd exposure Vaccination Monoclonal antibodies are antibodies that have been derived from a single B cell clone (i.e. identical specific antibodies) • An animal (e.g. mouse) is injected with a pathogen to stimulate production of specific plasma cells • The plasma cells are removed and fused with tumor cells capable of endless divisions • The hybridoma formed will mass-produce the antibody Vaccines contain attenuated forms of a pathogen (cannot cause the disease, but can stimulate an immune response) Monoclonal antibodies for hCG are used to test pregnancy • Results detected via enzyme-linked immunosorbant assay 1 0 1st 0 exposure 3 6 9 60 63 66 Time (days) Vaccines induce active immunity by stimulating the presence of memory cells (confers long-term immunity) Tumor cells Antigen When exposed to the actual pathogen, the memory cells will trigger a significantly faster and stronger immune response • Periodic booster shots may still be required Smallpox was the first disease eradicated by vaccination Mouse Plasma cells Hybridoma Antibody (monoclonal)