The Immune System

2. The Immune System The body’s protective response to invading foreign organisms

3. Immune System: Functions • Protects from pathogens and foreign molecules • Parasites • Bacteria • Viruses • Removes dead/damaged cells • Attempts to recognize and remove abnormal cells

4. Immune System: Pathologies • Incorrect responses • Autoimmune disease • Overactive responses • Allergies • Lack of response • Immunodeficiency disease (AIDS)

5. Body Defenses: Two Lines • First line of defense • Physical and chemical barriers: • Skin, epithelial linings, and cilia • Acids, mucous, and lysozymes • Second line of defense • Innate, non-specific, immediate response • Acquired; attack a specific pathogen (antigen)

6. 3 processes needed for immunity: Inflammation Immunity Antibody-mediated/Humoral Cell-mediated Immunity

7. Lymphatic System: Anatomy Figure 24-2a

8. Key Cells of the Immune System Leukocytes (white blood cells)

9. Cells of the Immune System

10. Figure 24-4

11. Cells • Leukocytes: 5 major categories. • Neutrophils: Phagocytic cells that wander throughout the connective tissue destroying bacterias. • Eosinophils: Phagocytic cells that destroy allergens, antigen & anti-body complexes, & some inflammatory chemicals. • Surround larger parasites & attack them with enzymes to weaken or destroy them. • Defend against allergies & parasitic worm infections. • Basophils: Helper cells that secrete vasodilators & anticoagulants in order to speed other leukocytes to the infected zone.

12. Cells • Lymphocytes: A variety of cells active in the immune response. • Natural Killer Cells (NK Cells): Attack any cell with an unusual plasma membrane, such as cells that are infected by a virus or have become cancerous. • Cytolysis: Perforin protein is injected into the cell to cause it to “explode”. • Granzymes: Cause the cell to self-destruct. • Found in the spleen, red bone marrow, & lymph nodes. • Monocytes: Wandering cells that eventually turn into macrophages.

13. Inflammation(natural immunity) • Inflammation: One of the body’s most common responses to tissue damage. Occurs in roughly the same way in any tissue. • Four Cardinal signs of Inflammation: • Redness • Swelling • Heat • Pain

14. Major cells of inflammation: • Neutrophils: • 1st line defense against invaders in blood and ECF. • Destroy invaders by phagocytosis • Absolute neutrophil count is used to determine a person’s risk for infection

15. Major cells of inflammation: • Macrophages • Preform phagocytosis, repair injured tissue • Stimulate CMI + AMI • Long life span and plenty of energy to degrade many foreign proteins.

16. Cells Phagocytes Cells under attack release histamine. Purpose is to engulf and destroy invaders

17. Major cells of inflammation: • Basophils • Cause the manifestation of inflammation • Contain chemicals that act on b. vessels • Heparin inhibits blood clotting • Histamine constricts small veins & respiratory smooth muscle

18. Major cells of inflammation: • Eosinophils • Act against infestations of parasitic larvae • Can inhibit and induce inflammation • Number increases during allergic reaction

21. Immune System Specific Immune Defenses: Cells specifically geared toward fighting certain invaders, and remembering previous foreign invaders so that they can be rapidly eliminated in the future.

22. Immune System • Two Divisions of the Immune System: • Humoral Immunity aka Antibody-Mediated Immunity: • Driven by B cells. • Cell-mediated immunity: • Driven by T cells.

23. What is specific immunity? • Specific response • Memory for future reinvasion • Antibody-based • B cells primary actors • Cell-mediated • T cells only

24. Antigens • Antigen: • Typically large molecules, often proteins.

25. Antigen Processing • Major Histocompatability Complex (MHC): “Self-antigens” that are unique to all of your body cells except red blood cells. • Help T-cells recognize which cells are foreign. • MHC-1s: Cells that posses MHC and are labeled “you” by the T-cells.

26. Antibodies • Also known as immunoglobulins • Some act as labels to identify antigens for phagocytes • Some work as antitoxins • i.e. block toxins for e.g. those causing diphtheria and tetanus • Some attach to bacteria making them less active • easier for phagocytes to engulf • Some cause agglutination (clumping together) of bacteria

27. Humoral Immunity • Humoral Immunity aka Antibody-Mediated Immunity • B cells (B-lymphocytes) produce antibodies to engage in a complex purging process. • Immunoglobulins (Igs) • Antibodies made up of glycoproteins called globulins. • Antigen-Binding Site • Tips of each chain are called variable regions & are areas where the antibody attaches to the antigen.

28. B -Lymphocytes • Receptors recognize an antigen on the surface of the invader, the B-cell divides rapidly. • Antigens are presented to the B-cells by macrophages

29. B -Lymphocytes

31. When help arrives . . . Antigen & T-helper cell Naïve cell Proliferation of cell line The T-helper cell receptor “docks” with the B cell’s MHComplex B cells proliferate . . .

32. B cells differentiate into . . . Antigen & T-helper cell antibodies memory • Antibody producing cells [attack mode] • Memory cells [remembers & future protection]

33. AMI in summary • An invaders attacks… • Antigen is phagocytized by the B cell • Broken into non-infective pieces & attached to MHC which is placed on the cell membrane surface here it is recognized by the helper T cell…

34. Cell Mediated Immunity • Cellular Immunity: • Lymphocytes directly attack & destroy foreign cells & infected host cells. • T-Cells or T-lymphocytes activated by a specific antigen.

35. Cellular Immunity • Types of T-Cells involved in Cell-mediated Response: • Cytotoxic T-Cells: Responsible for actual attacking of the foreign body or infected cell. • Helper T-Cells: Stimulate other helper T-cells, cytotoxic T-cells, and B cells. • Suppressor T-Cells: Help regulate the attack & prevent tissue destruction. • Memory T-Cells: Remain as an immune response and stimulate faster responses if the same antigen invades again.

36. T Lymphocytes: Cell-Mediated Roles of T lymphocytes and NK cells in cell-mediated immunity Figure 24-16

37. What happens in a cell-mediated response? • The key events: • Surveillance and recognition • Attack • Memory

39. Types of Immunity Active Immunity: You encountered the pathogen yourself and developed your own antibodies to it. Passive Immunity: You received antibodies directly introduced into the body. Naturally Acquired: Antibodies are received through natural means. Artificially Aquired: Antibodies are received through artificial (scientific) methods.

41. Vaccination A preparation containing antigenic material: • Whole live microorganism • Dead microorganism • Attenuated (harmless) microorganism • Toxoid (harmless form of toxin) • Preparation of harmless ags

42. Disorders of the Immune System • Hypersensitivity Disorders • Allergy • Anaphylaxis • Transfusion reactions, transplant rejection • Immunodeficiency Disorders • HIV/AIDS • Autoimmune • Systemic lupus erythematosus, rheumatoid arthritis etc.

43. Hypersensitivity • Excessive reaction to an antigen (allergen) to which most people do not react • Includes • Allergies • Transplant reaction • Transfusion

44. Hypersensitivity Disorders • Reaction may be Local (gastrointestinal, skin, resp, conjuctaval) or systemic (anaphylactic) • Q: What factors affect the severity of a hypersensitivity reaction? • Host response • Exposure amount • Nature of the allergen • Route of allergen entry • Repeated Exposure (

45. Hypersensitivity Assessment • Subjective Information • Pruritus, nausea and uneasiness • History of present illness • Onset, frequency and duration of symptoms • Nature and progression of s/s • Possible exposures of known allergens/common allergens • Chronic, seasonal or single episode • Aggravating & alleviating factors

46. Hypersensitivity Assessment • Physical Assessment • Respiratory • S/Sx caused by Bronchoconstriction—SOB, difficulty breathing, wheezing, & coughing • Sneezing, excessive nasal secretions, inflamed nasal membranes • Cardiovascular • S/Sx caused by Vasodilation—Flushing, Hypotension, Edema • Shock followed by cardiovascular collapse and respiratory arrest • GI • Nauses, vomiting, diarrhea • Skin • Rash, areas of raised inflammation (urticaria/hives)

47. Hypersensitivity Studies & Medical Management • Studies—CBC, Total serum IgE levels, skin testing • Medical Management • Immediate intervention • Symptom management & long term control • Environmental control

48. Hypersensitivity—Medications • Oxygen—if respiratory assistance needed • Bronchodilators • Emergency bronchodilator—Epinephrine 1:1,000 SQ–Anaphylactic reactions (may need to following with IV Epi) • Antihistamines—symptom management & long term control • First Generation—Prototype Diphenhydramine • Second Generation—Prototype Fexofenadine • Leukotrieneinhibitors—Inhibits the release of leukotrienes from mast cells & basophils) • Prototype—montelukast (Singulair) • Steroids—symptom management & long term control • Systemic—Prototype Prednisone

49. Allergies • When the immune system responds to harmless substances • Allergens – antigenic substances • Allergens include house dust, animal skin, pollen, house dust mite and its faeces

50. Immunoglobulins and Allergic Response • Allergen triggers the B cell to make IgE antibody, which attaches to the mast cell; when that allergen reappears, it binds to the IgE and triggers the mast cell to release its chemicals