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Immunity

Immunity. The specific immune response. Three Lines Of Defense. Non-specific immunity: all invaders treated the same way. Specific immunity: a specialised response. STRUCTURE AND FUNCTION OF THE LYMPHATIC SYSTEM. The lymphatic system is part of the immune system.

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Immunity

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  1. Immunity The specific immune response

  2. Three Lines Of Defense Non-specific immunity: all invaders treated the same way Specific immunity: a specialised response

  3. STRUCTURE AND FUNCTION OF THE LYMPHATIC SYSTEM • The lymphatic system is part of the immune system. • It is compromised of vessels and lymph nodes. The vessels are separate from the circulatory system, but return fluids and proteins into the blood. • Lymph vessels have valves preventing the backflow of lymph fluid. Lymph fluid is filtered by the lymph nodes which swell when infected. • The lymph nodes also contain white blood cells and have a vital role in the specific immune system.

  4. Source: http://www.womentowomen.com/images/lymphatic-system.png

  5. Specific immunity • Cells called LYMPHOCYTES are employed to target and remember particular invaders • Lymphocytes are produced in the bone marrow All lymphocytes are produced in bone marrow Mature in thymus gland = T lymphocytes (T cells) Mature in bone marrow = B lymphocytes (B cells)

  6. Identifying the foreigners • Cells show proteins (coded by their DNA) on the outer surface to identify themselves • These genes are called Major Histocompatibility Markers (or MHCs) • Class 1 markers: found on all cells except red blood cells • Class 2 markers: Found only on T cells, B cells and some macrophages

  7. Self markers • At the heart of the immune response is the ability to distinguish between self and non-self. • Every body cell carries distinctive molecules that distinguish it as "self." • Normally the body's defenses do not attack tissues that carry a self marker; rather, immune cells coexist peaceably with other body cells in a state known as self-tolerance. http://www.asparis.net/lowerschool/body/immune/immune_system_parts.htm

  8. Non-self markers • Foreign molecules, carry distinctive markers, shapes called epitopes that protrude from their surfaces. • The immune system can recognize many millions of different non-self molecules, and respond by producing molecules that can match and counteract each one of the non-self molecules. • Any substance capable of triggering an immune response is known as an antigen. An antigen can be a bacterium or a virus, or a part or product of one of these organisms. • Tissues or cells from another individual also act as antigens; that's why transplanted tissues are rejected as foreign. http://www.asparis.net/lowerschool/body/immune/immune_system_parts.htm

  9. Immune cell Self antigens / markers Non-self receptors Self receptors

  10. B Cells • Mature in bone marrow • Immunity with B cells = humoral immunity • Each display a different marker/antigen/immunoglobulin • Bind to one specific kind of foreign antigen

  11. Response to foreign antigen • When a B cell binds to its complement foreign antigen, it replicates rapidly • Produces clonal cells (plasma cells): produce antibodies (which have a variety of effects on the invader) • Also produce B Memory cells, which quickly act on any secondary infections by the same agent.

  12. Survive for years, or even a lifetime. Provide immunity. Recovery: less antibody-producing cells produced. Cloned plasma cells die quickly Source: http://www.purina.com.au/purinaone/images/articles/bcells.gif

  13. Clonal Selection Theory • Foreign antigen must pass many immunoglobulins before “selecting” the right one to clone

  14. Antibody production Memory cells are very efficient at mounting a quick response to any secondary infection by the same antigen (or pathogen). This is called IMMUNITY. Source: http://www.purina.com.au/purinaone/images/articles/antibody_concentration.gif

  15. Structure of antibodies 4 Polypeptide chains: two light, two heavy 5 types of heavy chains, which build different types of immunoglobulin (Ig) Source: http://www.biology.arizona.edu/immunology/tutorials/antibody/graphics/antibody.gif

  16. Function of immunoglobulin/antibody

  17. T cells • Similar to B cells in the following ways: • Have specific recognition sites • Reproduce rapidly • T-memory cells form • Immunity involving T cells = cellular immunity

  18. Types of T Cells • Helper T cells (Th): once they have phagocytised a foreign cell, they display foreign markers to alert other cells, and to stimulate B cells to produce antibodies. • Cytotoxic T cells (Tc): kill “self” cells infected with a virus. Self cells display viral antigens. Tc punches hole in cell membrane. Some Tc kill cancer cells

  19. A reminder: Immune cells all travel throughout the body using the lymphatic system.

  20. Source: http://www.transferfactor-live.com/images/img5329671.jpg

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