Overview of the Immune System

1. Overview of the Immune System Efren N. Aquino M.D.

4. The Formed Elements • Produced in red bone marrow • Hematopoietic (blood-forming) stem cells can develop into any blood cell • Stem cells are short-lived tissue cells

6. Lymphoid tissueis primarily localized in the lymph nodes of the lymphatic system and is also in the spleen, thymus, and bone marrow. • Several classes of white cells are produced, including the lymphocytes, monocytes and macrophages.

7. How Do Infections Occur? • Factors involved in infection 1. Portal of entry 2. Virulence of organism • Aggressiveness • Toxin production 3. Dose (number) of pathogens 4. Individual condition (predisposition) to infection

8. The Immune System • Types of general body defenses against disease • Nonspecific defenses • Effective against any harmful agent • Specific defenses • Effective against a certain agent only

9. Body Defenses: • Successive lines of defense Simple outer barriers More complicated responses Immunity (ultimate defense mechanism)

10. Nonspecific Defenses • Chemical and mechanical barriers • Phagocytosis • Natural killer cells • Inflammation • Fever • Interferon

11. Skin Mucous membranes Cilia Body secretions Tears Perspiration Saliva Digestive juices Reflexes Sneezing Coughing Vomiting Diarrhea Chemical and Mechanical Barriers

12. Phagocytosis • White blood cells take in and destroy waste and foreign material • Neutrophils • Macrophages

13. Natural Killer Cells • Type of lymphocyte • Can recognize body cells with abnormal membranes • Found in lymph nodes, spleen, bone marrow, blood • Secrete protein that breaks down cell membrane

14. Inflammation • Infection is inflammation caused by pathogens • Inflammatory reaction • Heat, redness, swelling, pain • Leukocytes enter tissue • Pus is produced • Lymph nodes enlarge

15. English Redness Heat Swelling Pain Loss of function Latin Rubor Calor Tumor Dolor Functio laesa The classic signs and symptoms of acute inflammation:

16. Fever • As phagocytes work, they release substances that raise body temperature • Stimulates phagocytes • Increases metabolism • Decreases some organisms’ ability to multiply

17. Interferon • Group of substances that prevent nearby cells from producing more virus • IFN a (alpha) • IFN b (beta) • IFN g (gamma) • Also acts nonspecifically on immune system cells

18. Specific Defenses: • Immunity • Power to overcome a specific disease agent • Inborn immunity • Inherited in genes • Acquired immunity • Develops after birth • Acquired naturally or artificially • Active or passive

19. Types of immunity.

20. Inborn Immunity • Differences in physical constitution • Species immunity • Individual immunity

21. Acquired Immunity • Develops in a person • During lifetime • From encounters with specific harmful agents

22. What is the difference between inborn and acquired immunity?

23. Antigens • Foreign substances that • Enter body • Induce immune response of certain lymphocytes • T cells • B cells

24. T Cells • Originate in stem cells in bone marrow • Change to T cells in thymus • Become sensitized to specific antigens • Produce cell-mediated immunity • Cytoxic T cells • Helper T cells - interleukins • Inhibitory/Regulatory T cells • Memory T cells • Macrophages

25. Activation of T-cells

26. Memory T-cells

27. 1. Cytoxic T cells - destroy • 2. Helper T cells - interleukins • 3. Regulatory T cells - inhibit • 4. Memory T cells – don’t engage • Cluster of Differentiation 4 : CD4 - a glycoprotein that is found primarily on the surface of helper T cells; "CD4 is a receptor for HIV in humans"

28. B Cells and Antibodies • Antibody (Ab) also known as immunoglobulin (Ig) is a substance produced in response to antigen • Manufactured by B cells (B lymphocytes) • Must mature in fetal liver or in lymphoid tissue • Provides humoral immunity • Contained in gamma globulin fraction of blood plasma

29. Activation of B cells. The B cell combines with a specific antigen. The cell divides to form plasma cells, which produce antibodies. Some of the cells develop into memory cells, which protect against reinfection.   What two types of cells develop from activated B cells?

31. What is an antibody? What type of cells produce antibodies?

32. The Antigen–Antibody Reaction • Complement is the enzymatic activity of a group of nonspecific proteins in blood: • Coats foreign cells • Destroys cells • Promotes inflammation • Attracts phagocytes

34. Naturally Acquired Immunity • Immunity acquired through contact with a specific disease organism • Active immunity • Passive immunity

35. What is the difference between the active and passive forms of naturally acquired immunity?

36. Artificially Acquired Immunity • Vaccination (immunization) can cause a person’s immune system to manufacture antibodies • Preventive measure • Risk of side effects

37. Types of Vaccines • Live • Attenuated • Toxoid • Killed by heat or chemicals • Antigenic component • Genetically engineered

38. Boosters • Active immunity does not always last a lifetime • Repeated inoculations (booster shots) help maintain high titer of antibodies in the blood • Number and timing varies with vaccines

39. Passive Immunization • Acquired by administration of immune serum (antiserum) • Short-lived immunity • Used in emergencies • Often derived from animals • May cause sensitivity reaction

40. What is an immune serum and when are immune sera used?

42. DONE !! ?? .. Nah .. not yet