Immunity Quiz

Immunity

• Immunity is the body's defense system against harmful pathogens.
• Components of the immune system include lymph nodes, thymus, appendix, spleen, bone marrow, and Peyer's patches.
• The innate immune system includes neutrophils, mast cells, natural killer cells, eosinophils, basophils, macrophages, monocytes, and dendritic cells.
• The adaptive immune systems includes memory T cells, cytotoxic T cells, helper T cells, plasma cells, B cell progenitor, and memory B cells
• The hematopoietic stem cell is the precursor of immune cells.

Active and Passive Immunity

• Active immunity:
  • Natural: Antibodies developed from infections.
  • Artificial: Antibodies developed from vaccines; may require boosters.
• Passive immunity:
  • Antibodies obtained from external sources like breast milk.
  • Artificial: Antibodies injected; no memory cells formed.

Types of Hypersensitivity Reactions

• Type I (Allergic Reactions):
  • Mediated by IgE
  • Onset within one hour.
  • Examples: Anaphylaxis, hives.
• Type II (Cytotoxic):
  • IgG or IgM mediated
  • Onset: Hours to days
  • Examples: Hemolytic anemia.
• Type III (Immune Complex):
  • Immune complex-mediated
  • Onset: 1-3 weeks
  • Examples: Serum sickness, lupus.
• Type IV (Cell-Mediated):
  • T-cell-mediated
  • Onset: Days to weeks
  • Examples: Contact dermatitis, poison ivy, asthma.

Allergies (Type I)

• Inappropriate immune response.
• Symptoms: Pruritus, urticaria, angioedema.
• Treatment: Antihistamines.

Anaphylaxis (Type I)

• Two or more body systems affected
• Faster onset, worse reaction.
• Treatment: Epinephrine, steroids, antihistamines.

Anaphylaxis Treatment

• Epinephrine: 0.3 mg IM for adults, 0.15 mg IM for children
• Autoinjector: Vastus lateralis.
• Repeat epinephrine 2 mg IN every 5 minutes as needed

Type II Hypersensitivity (Acute Hemolytic Reaction)

• Symptoms during a transfusion:
  • Systemic: chills, fever, hypotension, uncontrollable bleeding
  • Vascular: transfusion vein sensation
  • Lumbar region pain
  • Heart: increased heart rate
  • Chest: constricting pain
  • Urinary: hemoglobinuria, hyperbilirubinemia

Systemic Lupus Erythematosus (SLE, Type III)

• Chronic inflammatory disorder.
• Symptoms: butterfly rash, discoid skin rashes, disturbed body image.
• Treatment: sun protection, avoiding infections, promoting rest, monitoring infections, steroids, tapering steroids to avoid complications like Addison's crisis.

Type IV Hypersensitivity Reaction

• Examples: Asthma, contact dermatitis, poison ivy, local reactions (bites/stings).

HIV

• Chronic infection, impairs immune system.
• Transmission routes: sexual, parenteral, perinatal (blood, body fluids, placenta, delivery, breast-feeding).
• Reducing transmission risks is crucial.

HIV Stages

• Stage 0 (Acute): Normal lab values.
• Stage 1 (Chronic): CD4+ > 500.
• Stage 2 (Worse): CD4+ 200-499.
• Stage 3 (AIDS): CD4+<200.

Acquired Immunodeficiency Syndrome (AIDS)

• CD4+ T-cell count falls below 200 cells/mcL.

AIDS-Defining Conditions

• Cytomegalovirus retinitis, Pneumocystis jiroveci pneumonia, chronic intestinal cryptosporidiosis, HIV-related encephalopathy, Mycobacterium tuberculosis, invasive cervical cancer.

HIV Management

• Prevention of infection.
• Monitoring CD4+ counts.
• Antiretroviral drugs.
• Safe sex practices (condoms, dental dams, water-based lubricants, latex gloves).
• Monitoring for other infections.

HIV Pre-Exposure Prophylaxis (PrEP)

• PrEP drugs (e.g., Truvada): tenofovir/emtricitabine, one tablet daily.
• Effective for high-risk populations.
• Starts working after 7 days.
• Ineffective if two consecutive doses are missed.
• Monitor renal function, and HIV status every 3 months.
• Continue practices like safe sex.

Lyme Disease

• Caused by Borrelia burgdorferi.
• Stages:
  • Stage 1: Flu-like symptoms, arthralgias, erythema migrans.
  • Stage 2: Cardiac, respiratory, neurologic symptoms.
  • Stage 3: Arthritis, chronic fatigue, memory problems.
• Prevention/Early Detection: Avoid heavily wooded areas, wear light-colored clothing, use insect repellent, and check for ticks; remove ticks immediately, report bites, and follow-up with provider for testing within 4-6 weeks.

Transplant Rejection

• Hyperacute rejection: Minutes to hours, immune system triggers blood clots in the new organ, leads to organ failure.
• Acute rejection: 1 week to 3 months, inflammation in blood vessels and tissues of transplanted organ; potentially controlled with anti-rejection medication.
• Chronic rejection: Months to years, chronic inflammation and scarring, reduced blood flow and organ function.