The document summarizes key aspects of the immune system. It describes the components of the immune system including lymphoid structures, immune cells, and tissues responsible for immune cell development. It also discusses the nonspecific and specific immune responses, antibodies, immunity types, hypersensitivity reactions, and immunodeficiencies.

1. Chapter 7
Immunity

2. Immune System
 Responsible for body defenses
 Nonspecific response (defense)
• Examples: phagocytosis, inflammation
 Specific response (defense)
• Production of specific antibodies against foreign
substances
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3. Components of the Immune
System
 Lymphoid structures
 Lymph nodes
 Spleen
 Tonsils
 Intestinal lymphoid tissue
 Lymphatic circulation
 Immune cells
 Lymphocytes
 Macrophages
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4. Components of the Immune
System (Cont.)
 Tissues—immune cell development
 Bone marrow
• Origination of all immune cells
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 Thymus
• Maturation of T lymphocytes

5. Structures of the Immune System
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6. Elements of the Immune System
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 Antigens
 Self
• HLA proteins label cells of the individual.
• Immune system ignores self cells.
 Non-self
• Immune system recognizes specific nonself antigens as
foreign.
• Development of a specific response to that particular
antigen
• Memory cells produced to respond quickly to antigen

7. Antigens (Immunogens)
 Usually exogenous substances
 Cell surface antigens
 Proteins
 Polysaccharides
 Glycoproteins
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8. Cells
 Macrophages
 Initiation of immune response
 Develop from monocytes
 Part of the mononuclear phagocytotic system
 Engulf foreign material
 Display antigens of foreign material
 Secrete chemicals
• Examples: monokines, interleukins
 Present throughout the body
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9. Cells
 Lymphocytes
 T lymphocytes
• From bone marrow stem cells
• Further differentiation in thymus
• Cell-mediated immunity
• Cytotoxic T killer cells
• Helper T cells
• Memory T cells
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10. Cells (Cont.)
 Lymphocytes
 B lymphocytes
• Responsible for production of antibodies
• Humoral immunity
• Mature in bone marrow
 Proceed to spleen and lymphoid tissue
• Plasma cells
 Produce antibodies
• B memory cells
 Can quickly form clone of plasma cells
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11. Types of Immunity
 Humoral immunity: Antibodies are produced
to protect the body.
 Cell-mediated immunity (CMI): Lymphocytes
are programmed to attack nonself cells to
protect the body.
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12. Development of Cellular and
Humoral Immunities
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13. Antibodies and Immunoglobulins
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 IgG
 Most common in blood
 IgM
 First to increase in immune response
 IgA
 In secretions
• Tears
• Saliva and mucous membranes
• Colostrum

14. Antibodies and Immunoglobulins
(Cont.)
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 IgE
 Allergic response
 Causes release of histamine and other chemicals
 Results in inflammation
 IgD
 Attached to B cells
 Activates B cells

15. Review of the Major Components
of the Immune System
 Major components of the immune system and
their function
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16. Complement System
 Activated during immune reactions with IgG
or IgM
 Group of inactive proteins circulating in blood
 C1 to C9
 Causes cell damage and further inflammation
when activated
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17. Chemical Mediators
 Involved in inflammation and immune
reactions
 Examples: histamine, interleukins
 Variety of functions
 Signaling
 Causing cellular damage
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18. Diagnostic Tests
 Titer (titre)
 Measures levels of serum immunoglobulins
 Indirect Coombs’ test
 Detects Rh blood incompatibility
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 Elisa
 Detects HIV antibodies
 Used for a number of other diseases
 MHC typing
 Tissue matching before transplantation
procedures

19. Immunity
 Natural immunity
 Species-specific
 Innate immunity
 Gene-specific
 Related to ethnicity
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20. Immunity (Cont.)
 Primary response
 First exposure to antigen
 1 to 2 weeks before antibody titer reaches efficacy
 Secondary response
 Repeat exposure to the same antigen
 More rapid response, with efficacy in 1 to 3 days
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21. Primary and Secondary Immune
Responses
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22. Immunity
 Active natural immunity
 Natural exposure to antigen
 Development of antibodies
 Active artificial immunity
 Antigen purposefully introduced to body
 Stimulation of antibody production
 Immunization
 Booster immunization
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23. Immunity (Cont.)
 Passive natural immunity
 IgG transferred from mother to fetus:
• Across placenta
• Through breast milk
 Protection of infant for the first few months of life
or until weaned
 Passive artificial immunity
 Injection of antibodies
 Short-term protection
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24. Types of Acquired Immunity
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25. Tissue and Organ Transplant
Rejection
 Hyperacute rejection
 Immediately after transplantation
 Acute rejection
 Develops after several weeks
 Chronic, late rejection
 Occurs after months or years
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26. Immunosuppression
 Reduction of immune response to prevent
rejection
 Commonly used drugs
 Cyclosporine, azathioprine, prednisone
 High risk of infection
 Caused by immunosuppression
 Opportunistic organisms
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27. Hypersensitivity Reactions
 Type I hypersensitivity—allergic reactions
 Common
• Caused by allergen
• Skin rashes
• Hay fever
 Causative mechanism
• Exposure to allergen
• Development of IgEs
• Mast cells
 Complications
• Anaphylaxis
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28. Hypersensitivity Reactions
(Cont.)
 Type I hypersensitivity–allergic reactions
(Cont.)
 Hay fever: allergic rhinitis
• Nasal mucosa
 Food allergies
• Digestive tract mucosa
 Atopic dermatitis/eczema
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• Skin
 Asthma
• Bronchial mucosa

29. Type I Hypersensitivity
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30. Anaphylaxis: Anaphylactic Shock
 Severe, life-threatening
 Systemic hypersensitivity reaction
 Decreased blood pressure caused by release
of histamine
 Airway obstruction
 Severe hypoxia
 Can be caused by:
 Latex materials
 Insect stings
 Nuts or shellfish; various drugs
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31. Anaphylaxis (Cont.)
 Signs and symptoms
 Generalized itching or tingling, especially in oral
cavity
 Coughing
 Difficulty breathing
 Feeling of weakness
 Dizziness or fainting
 Sense of fear and panic
 Edema around eyes, lips, tongue, hands, feet
 Hives
 Collapse with loss of consciousness
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32. Effects of Anaphylaxis
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33. Signs and Symptoms of
Anaphylaxis
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34. Treatment for Anaphylaxis
 Requires first aid response:
 Administer EpiPen if available
 Call 911 (many paramedics can start drug
treatment and oxygen)
 Treatment in emergency department:
 Epinephrine
 Glucocorticoids
 Antihistamines
 Oxygen
 Stabilize BP
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35. Type II: Cytotoxic Hypersensitivity
 Antigen is present on cell membrane
 May be normal body component or exogenous
 Circulating IgGs react with antigen
 Destruction by phagocytosis or cytolytic enzymes
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 Example
 Response to incompatible blood transfusion

36. Type II Hypersensitivity
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37. Type III: Immune Complex
Hypersensitivity
 Antigen combines with antibody
 Forms immune complexes, deposited in tissue
 Activation of complement system
 Process causes inflammation and tissue
destruction
 Examples:
 Glomerulonephritis
 Rheumatoid arthritis
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38. Type III: Immune Complex
Reaction
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39. Type IV: Cell-Mediated or
Delayed Hypersensitivity
 Delayed response by sensitized T lymphocytes
 Release of lymphokines
 Inflammatory response
 Destruction of the antigen
 Examples:
 Tuberculin test
 Contact dermatitis
 Allergic skin rash
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40. Autoimmune Disorders
 Development of antibodies against own cells
or tissues
 Autoantibodies are antibodies formed against
self-antigens—loss of self-tolerance.
 Disorder can affect single organs or tissues
or can be generalized.
 Examples:
 Hashimoto thyroiditis, systemic lupus
erythematosus, rheumatic fever, myasthenia
gravis, scleroderma, pernicious anemia
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41. The Autoimmune Process
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42. Type IV: Cell-Mediated Delayed
Hypersensitivity
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43. Systemic Lupus
Erythematosus (SLE)
 Chronic inflammatory disease
 Affects a number of organ systems
 Characteristic facial rash—“butterfly rash”
 Affects primarily young women
 Incidence is higher in African Americans,
Asians, Hispanics, Native Americans
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44. Butterfly Rash Associated with SLE
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45. SLE
 Large number of circulating autoantibodies
 Against DNA, platelets, erythrocytes
 Formation of immune complexes
 Deposited into tissues
 Inflammation and necrosis
 Vasculitis develops in many organs.
 Impairs blood supply to the tissues
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46. SLE (Cont.)
 Sings and symptoms vary because of organ
involvement but commonly include:
 Arthralgia, fatigue, malaise
 Cardiovascular problems
 Polyuria
 Diagnostic test
 Serum antibodies, LE cells, other blood work
 Treatment
 Usually treated by a rheumatologist
 Prednisone (glucocorticoid)
 Nonsteroidal anti-inflammatory drugs
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47. Common Manifestations of SLE
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48. Immunodeficiency
 Partial or total loss of one or more immune
system components
 Increased risk of infection and cancer
 Primary deficiencies
 Basic developmental failure somewhere in the
system
 Secondary or acquired immunodeficiencies
 Loss of the immune response from specific causes
 Can occur at any time during the life span
• Infections, splenectomy, malnutrition, liver disease,
immunosuppressant drugs, radiation, chemotherapy
(cancer)
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49. Immunodeficiency (Cont.)
 Predisposition to the development of
opportunistic infections
 Caused by normal flora
 Usually difficult to treat because of
immunodeficiency
 Prophylactic antimicrobial drugs may be used
prior to invasive procedures.
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50. Acquired Immunodeficiency
Syndrome (AIDS)
 AIDS—chronic infectious disease caused by
the human immunodeficiency virus (HIV)
 HIV destroys helper T cells—CD4
lymphocytes
 Loss of immune response
 Increased susceptibility to secondary
infections and cancer
 Prolonged latent period
 Development may be suppressed by
antivirals
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51. AIDS (Cont.)
 HIV-positive individual
 Virus is known to be in the body.
 No evidence of immunosuppression
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 AIDS
 Marked clinical symptoms, multiple complications
 Individual often identified as HIV-positive
before development of AIDS
 Current therapies start if HIV infection is
diagnosed in the early stages.

52. Stages in the Development
of AIDS
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53. History of AIDS
 First case recognized in 1979; HIV identified
in 1984
 Evidence of earlier sporadic cases
 Now considered to be a pandemic
 Occurs in men and women
 2006, CDC: 1 million cases in North America
 2007, UN: 33 million cases globally; 22
million of those in sub-Saharan Africa
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