Flashcards in Patho: Immune Deck (28)
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Defense Mechanisms
First line of defense: skin
Second line of defense: body’s inflammatory
response
Third line of defense: immunity
Leukocytes
- Granulocytes
- Monocytes
- Lymphocytes
Lymphoid organs and tissues
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Types of Immunity
Natural immunity
Active Immunity
- Naturally acquired: having disease
- Artificially acquired: immunizations
Passive Immunity
- Naturally acquired: neonates receive antibodies from mothers
- Artificially acquired: injecting serum with antibodies
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Immunity
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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Types of Immunizations/ Vaccines
Inactivated vaccines
Live, attenuated vaccines
Toxoids
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Recommended Immunizations for Adults
Measles-mumps-rubella (MMR)
Tetanus and diphtheria toxoids (Td)
Hepatitis B Influenza
Pneumonococcal
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Altered Immune Responses: Hypersensitivity
- I: Immediate hypersensitivity
- II: Cytotoxic hypersensitivity
- III: Immune hypersensitivity
- IV: Delayed hypersensitivity
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Type 1: Immediate Hypersensitivity
Clinical Manifestations:
Mild
- Hives
- Seasonal allergic rhinitis
- Eczema
More problematic symptoms
- Throat constriction
- Localized edema
- Wheezing
- Tachycardia
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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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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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Type II: Cytotoxic Hypersensitivity
Tissue specific reactions:
- Cells destroyed by antibody and complement - Cell destruction by phagocytosis
- Toxic products produced
- Antibody dependent cell mediation
- Cell malfunction
Manifestations are determined by tissue or organ affected
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Type II: Immune Hypersensitivity
Immune complex mediated reactions
Antigen-antibody reactions
Body fails to identify self and reacts against itself
Genetic component
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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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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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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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Measuring Level of Immunity
Serum immunoglobulins
- Measure levels of immunoglobulins
Antibody titer testing
- Identify antibody titer levels
Skin testing
- Detect impaired cell-mediated immunity
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Tests to Detect Hypersensitivity
- Radioallergosorbent test (RAST)
- Skin tests
- Prick test
- Intradermal
- Patch
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Serum Assays
Antinuclear antibody (ANA) test
- Specific to screen for systemic lupus
erythematosis
Rheumatoid factor (RF)
- Specific to screen for rheumatoid arthritis
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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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HIV Risk Factors
Hemophiliacs
Patients who received a transfusion with HIV-
infected blood or blood products
Newborns and breast-fed infants of HIV-
infected mothers
Injection drug users
Partners having unprotected sex with those
infected
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HIV: The body's response
The body’s response to HIV infection
- Mounts a defense against the HIV virus through antibodies and T cells
- About 12 weeks after infection, the body produces enough antibodies to be detected by standard HIV test
- HIV viral load begins to drop, indicating partial
effectiveness of the body to rid itself of HIV
- CD8 cells drop drastically in the late stages, and CD4 cells slowly decline throughout the whole infection
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Stages of HIV: Initial / Latent
Initial stage
- Lasts 4 to 8 weeks
- High levels of virus in the blood Generalized flulike symptoms
Latent stage
- Lasts 2 to 12 years
- Virus is inactive
- Levels are high in the lymph nodes but low in the blood
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Stages of HIV: Third Stage
Lasts 2 to 3 years
Patient experiences opportunistic infections
TH CD4 cells are usually
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AIDS
HIV-positive individual
- Virus is known to be in the body.
- No evidence of immunosuppression
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.
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Diagnosis of Aids
AIDS is diagnosed when an individual with HIV develops at least one of these conditions:
- Pneumocystis pneumonia
- Recurrent bacterial pneumonia
- Chronic herpes simplex virus infection
- Esophageal candidiasis
- Extrapulmonary tuberculosis
- Kaposi’s sarcoma
- Cytomegalovirus disease (other than liver, spleen or lymph nodes)
- Central nervous system toxoplasmosis
- HIV encephalopathy
- Extrapulmonary cryptococcosis (including meningitis)
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HIV Manifestations
Initial stage
- Generalized flulike symptoms
Latent stage
- May have no symptoms initially
- Eventually, frequent and persistent infections
- Fever, night sweats, swollen lymph nodes, headache, skin lesions, sore throat, dyspnea, burning with urination, or diarrhea
- Extreme fatigue and weight loss
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HIV Complications
AIDs Dementia Complex- confusion cognitive impairment, memory loss, loss of coordination, balance, depression, eventually cannot talk or move, seizures then coma
Opportunistic Infections- Candida, fungal
TB
Cancers- kaposi’s sarcoma
Non-Hodgkins or Hodgkins lymphoma
Wasting syndrome
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HIV Complications
Pneumocystis jiroveci pneumonia
- Acquired by inhalation
- Second leading cause of death in AIDS patients
- Cysts prevent the exchange of gases - Shortness of breath on exertion, fever, and a
nonproductive cough
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