physio

1. Humoral (Antibody-Mediated) Immunity Involves production of antibodies against foreign antigens. Antibodies are produced by a subset of lymphocytes called B cells. B cells that are stimulated will actively secrete antibodies and are called plasma cells. Antibodies are found in extracellular fluids (blood plasma, lymph, mucus, etc.) and the surface of B cells. Defense against bacteria, bacterial toxins, and viruses that circulate freely in body fluids, before they enter cells. Also cause certain reactions against transplanted tissue.

3. B cells develop from stem cells in the bone marrow

4. After maturation B cells migrate to lymphoid organs (lymph node).

6. Clonal Selection of B Cells is Caused by Antigenic Stimulation

9. B Lymphocytes Production of antibodies Stimulate production of memory cells Transformed into plasma cells

10. Mechanism of activating clone of lymphocyte Activation of B lymphocyte is by antigen attached to antibody in the cell membrane Activation of T lymphocyte is by surface receptor proteins (T-cell marker) on the surface of the membrane

11. Role of macrophage in activation process Most invading organism are first phagocytized by macrophages Macrophages pass these antigens to the lymphocytes This activates specific lymphocytic clones In addition, Macrophages secrete special activating substance (interleukin-1) that promote growth and reproduction of specific lymphocyte

12. Role of macrophage in activation process Most invading organism are first phagocytized by macrophages Macrophages pass these antigens to the lymphocytes This activates specific lymphocytic clones In addition, Macrophages secrete special activating substance (interleukin-1) that promote growth and reproduction of specific lymphocyte

13. Role of the T cells in activation B lymphocyte Some of the T cells called helper cells secret substance lymphokines activate B lymphocyte Without the aid of T helper cells, the quantity of antibodies formed by B lymphocyte is usually low

14. Antibodies Immunoglobulins are a group of proteins (gamma globulins) produced by the body from B lymphocytes and plasma cells in response to presence of foreign bodies (antigens). They constitute 20% of all plasma proteins Antibody consist of two polypeptide building blocks, a heavy chain and light chain Each antibody chain has a variable portion and constant portion

15. Classes of antibodies There are five classes of antibodies IgM, IgG, IgA, IgD and IgE IgG consist of 75% of the antibodies of the normal person. IgE involve in allergy IgM effective in protecting the body against invader

16. ImmunoglobulinFunctions lgG Main form of antibodies in circulation: production increased after immunization; secreted during secondary response lgA Main antibody type in external secretions, such as saliva and mother’s milk lgE Responsible for allergic symptoms in immediate hypersensitivity reactions lgM Function as antigen receptors on lymphocyte surface prior to immunization; secreted during primary response lgD Function as antigen receptors on lymphocyte surface prior to immunization; other functions unknown Antibodies

18. Mechanism of action of antibodies Direct attack on the invader Activation of the complement system

19. Direct action of antibodies on invading agent Agglutination: large particle with antigen are bound together into clump Precipitation: Molecular complex of soluble antigen and antibody become insoluble Neutralization: Antibodies cover the toxin side of antigen Lysis: Attacking membrane of cellular agent

20. Complement system for antibody action Complement : describes system of about 20 proteins, many of which enzyme precursors The principal actors in the system are 11 proteins designated C1 through C9, B and D The enzyme precursors are inactive and they become activated by classic pathway Classic pathway initiated by antigen-antibody reaction

21. Classic Pathway Opsonization and phagocytosis: Activate phagocytosis by neutrophils and macrophages causing these cells to engulf the bacteria to which antigen-antibody complex are attached Lysis: The effect is rupturing the bacteria cell membrane Agglutination: invading organism adhere to one another

22. Classic Pathway Neutralization of viruses: attach the structure of some viruses Chemotaxis: Initiate chemotaxis of neutrophil and macrophages Activation of mast cells and basophils: Release of histamine and other products Inflammatory effects: increase blood flow, increase capillary leakage of proteins

23. Consequences of Antibody Binding