Patho: Immune Flashcards
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
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
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
Types of Immunizations/ Vaccines
Inactivated vaccines
Live, attenuated vaccines
Toxoids
Recommended Immunizations for Adults
Measles-mumps-rubella (MMR)
Tetanus and diphtheria toxoids (Td)
Hepatitis B Influenza
Pneumonococcal
Altered Immune Responses: Hypersensitivity
- I: Immediate hypersensitivity
- II: Cytotoxic hypersensitivity
- III: Immune hypersensitivity
- IV: Delayed hypersensitivity
Type 1: Immediate Hypersensitivity
Clinical Manifestations: Mild - Hives - Seasonal allergic rhinitis - Eczema More problematic symptoms - Throat constriction - Localized edema - Wheezing - Tachycardia
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
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
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
Type II: Immune Hypersensitivity
Immune complex mediated reactions
Antigen-antibody reactions
Body fails to identify self and reacts against itself
Genetic component
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
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
Tissue and Organ Transplant Rejection
Hyperacute rejection - Immediately after transplantation Acute rejection - Develops after several weeks Chronic, late rejection - Occurs after months or years
Measuring Level of Immunity
Serum immunoglobulins - Measure levels of immunoglobulins Antibody titer testing - Identify antibody titer levels Skin testing - Detect impaired cell-mediated immunity
Tests to Detect Hypersensitivity
- Radioallergosorbent test (RAST)
- Skin tests
- Prick test
- Intradermal
- Patch
Serum Assays
Antinuclear antibody (ANA) test - Specific to screen for systemic lupus erythematosis Rheumatoid factor (RF) - Specific to screen for rheumatoid arthritis
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
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
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
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
Stages of HIV: Third Stage
Lasts 2 to 3 years
Patient experiences opportunistic infections
TH CD4 cells are usually
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.
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)
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
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
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
Diagnostic Tests
HIV antibodies blood test
ELISA
West Blot test
Decrease in T-helper cells
