Immunology & Hypersensitivity Lecture – Comprehensive Study Notes

Concepts Woven Through Immunity Lectures

• Caring, teaching & learning, clinical judgment, collaboration
• Apply across oncology, immunology, pediatrics, etc.
• Nursing duty: recognize individual fears (e.g., contagious pts., own immunocompromise)
• Use clinical‐judgment model:
  • Recognize cues
  • Analyze cues
  • Prioritize hypotheses
  • Generate solutions
  • Take action → evaluate
• Collaborators: infectious-disease MD, allergist, community nurse, patient & family

Study-Tip Advice From Instructor

• Create broad → sub-category outlines
• Color-code for visual memory
• Multiple learning modalities (visual, auditory, hands-on)

Immune-System Overview

• Protective system to destroy invaders
• Humoral (B-cell, antibody) vs. cell-mediated (T-cell) immunity
• IgE: dominant antibody in allergies/hypersensitivity

Hypersensitivity Reactions (Types I – IV)

Type I Immediate / IgE-Mediated

Anaphylaxis (Systemic Severe Allergy)

• Needs prior exposure → massive IgE & histamine release on re-exposure
• Patho: broncho-constriction, laryngeal edema (stridor), widespread vasodilation → \downarrow BP, \uparrow HR → anaphylactic shock
• Priority: Maintain airway; give 100 % O₂ via non-rebreather
• FIRST drug: IM/IV epinephrine 0.3–0.5 mg (adults) → bronchodilation + vasoconstriction
• Adjuncts: diphenhydramine 25–50 mg, corticosteroids (methyl-pred 125 mg), vasopressors (dopamine, norepi) if hypotension persists, possible intubation/ventilation
• Pt education: carry EpiPen, avoid allergen, medical-alert ID

Allergic Rhinitis

• Most common respiratory allergy (“hay fever”)
• Sneezing, itching, rhinorrhea, watery eyes
• Linked triad in children: allergic asthma → allergic rhinitis → atopic dermatitis (eczema)
• Management: non-sedating antihistamines (Claritin, Zyrtec, Allegra), intranasal steroids, biologics (Dupixent ®) for uncontrolled disease; identify & avoid triggers (dust, ragweed, pets)

Atopic Dermatitis (Eczema)

• Chronic, pruritic, inflammatory skin response (esp. flexor surfaces, neck, groin)
• Exacerbated by allergens, seasonal factors
• Nursing care:
  • Lukewarm Aveeno/baking-soda baths
  • Thick emollient ointments (vit A&D, petrolatum); wrap with plastic to enhance absorption; teach “pat/stroke—not scratch”
  • Topical steroids for flares; severe cases → immunomodulators (Protopic®, Elidel®) or biologic (Dupixent®)
  • Monitor for secondary infection (impetiginization, MRSA) → mupirocin (Bactroban)

Urticaria (Hives)

• Raised, pruritic wheals; causes include foods, drugs, thyroid disease, malignancy
• Tx: antihistamines, corticosteroids; epi if systemic compromise

Angioedema

• Deep dermal/sub-mucosal swelling (face, lips, eyelids, airway); can be drug induced (ACE-I) or allergic
• Management identical to anaphylaxis; secure airway early

Type II Cytotoxic / Antibody-Mediated

Hemolytic Transfusion Reaction

• Wrong ABO/Rh blood → antibodies bind donor RBC → complement lysis → intravascular clots
• S/S within minutes: chest pain, back/flank pain, fever, hypotension, dyspnea, hemoglobinuria
• Interventions:
  • STOP transfusion, keep line patent with 0.9\,% NS using new tubing wide open
  • Trendelenburg for shock; rapid VS; call Rapid Response
  • Send blood bag + tubing and blood samples (direct/indirect Coombs) to blood bank
  • Treat with epi, high-dose steroids (500\,\text{mg} solu-medrol), vasopressors; may need dialysis if renal damage
  • Prevention: type & screen, cross-match, 2-nurse verification
  • ABO facts: O = universal donor; AB = universal recipient; Rh- negative cannot receive Rh+ blood

Type III Immune-Complex / IgG–IgM

Serum Sickness

• Antigen–antibody complexes deposit in vessels/tissues after exposure to non-human proteins (antivenom, biologics) or drugs (penicillin, sulfa)
• Delayed 7–21 days
• Manifestations: fever >38.5\,^{\circ}\text{C}, urticaria, arthralgia/myalgia, lymphadenopathy, ↑WBC, ↑ESR
• Tx: stop offending agent, antihistamines, NSAIDs, corticosteroids, analgesics; educate pt to wear allergy ID

Type IV Delayed / Cell-Mediated (T-cell)

Contact Dermatitis

• Poison ivy/oak/sumac, nickel, cosmetics, latex
• Red, vesicular, weeping lesions appearing 24–48 h after contact
• Care: cleanse with brown soap, calamine, topical steroids, antihistamines, oatmeal/baking-soda baths; long-term severe cases → topical calcineurin inhibitors (Protopic®, Elidel®)

Latex Allergy

• Repeated exposure → dermatitis → potential progression to Type I anaphylaxis; use latex-free products, alert bracelet

Transplant Rejection

• Host T-cells attack graft → failure of tissue/organ
• Prevention: life-long immunosuppressants (cyclosporine, tacrolimus, prednisone, azathioprine)
• Teach infection control (handwashing, masks, avoid crowds) & drug adherence; monitor for organ-specific failure signs (e.g., ↓urine, flank pain in kidney graft)

Autoimmune Disorders

Pernicious Anemia (B₁₂-Deficiency)

• Antibodies destroy gastric parietal cells → loss of intrinsic factor → mal-absorption of vitamin B₁₂
• Also occurs post-gastrectomy/bypass (acquired)
• S/S: neuropathy (numb/tingling extremities, glossitis), fatigue, pallor, cold intolerance, \downarrow RBC, \downarrow Hgb (women 11–17\,g/dL; men 12–18\,g/dL), \downarrow Hct (35–55\,\%)
• Labs: low B₁₂, low RBCs, may see macrocytosis
• Tx: lifelong B₁₂ replacement (cyanocobalamin IM monthly or high-dose oral/SL); monitor B₁₂, CBC; teach diet high in B-complex; evaluate neuro improvement

Idiopathic Autoimmune Hemolytic Anemia

• Autoantibodies coat own RBCs → hemolysis
• S/S: fatigue, pallor, hypotension, dyspnea, jaundice (hemolysis), hepatosplenomegaly
• Tx: high-dose corticosteroids (watch side-effects: moon-face, weight gain, hyperglycemia, osteoporosis, buffalo hump), folic-acid 1\,mg daily, packed RBC transfusion if \text{Hgb}<7\,g/dL, possible splenectomy, immunosuppressants (cyclophosphamide)
• Nursing: monitor VS, glucose, infection signs; educate on steroid side-effects & tapering; vaccination pre-splenectomy

Steroid (Glucocorticoid) Pearls

• Common side-effects: moon face, weight gain, buffalo hump, hyperglycemia, immunosuppression, hirsutism, fluid-retention, osteoporosis, voice deepening (long-term high dose)
• Patient teaching: never stop abruptly (adrenal crisis), monitor blood glucose, Ca/Vit D supplementation, infection precautions, report black/tarry stools (GI bleed)

Numeric & Laboratory References

• Normal RBC count \approx 4.2\text{–}6.0\times10^{12}\,/\,L
• Normal hemoglobin: women 12\text{–}17\,g/dL; men 13\text{–}18\,g/dL
• Normal hematocrit: 35\text{–}55\,\%
• Epi dose anaphylaxis: 0.3\text{–}0.5\,mg IM (1:1000); may repeat q5–15 min

Nursing Diagnoses & Interventions (Cross-cutting)

• Impaired gas exchange → airway, O₂, epi
• Ineffective peripheral perfusion (transfusion rx.)
• Risk for impaired skin integrity (eczema, dermatitis)
• Anxiety (sense of impending doom in anaphylaxis)
• Ineffective self-health-management → education on allergen avoidance, medication use, emergency plan

Patient/Family Education Highlights

• Carry EpiPen; know when & how to use
• Allergen avoidance plans (pets, food, environmental)
• Wear medical-alert ID (drug allergies, transplant, latex)
• Correct use & storage of inhalers, nebulizers, B₁₂ injections
• Infection-prevention for immunocompromised & transplant pts.
• Recognize early signs of reaction: chest/back pain during transfusion, stridor/wheeze, new rash, swelling

Practical / Ethical / Real-World Connections

• School nurses must catalog allergies, teach EpiPen use, segregate peanut tables
• Family dynamics: educate caregivers to recognize wheezing/eczema flares (e.g., Ryan’s case)
• Steroid stewardship: balance life-saving anti-inflammatory effect vs. long-term harm
• Transfusion safety: rigorous identity checks prevent fatal errors; legal/ethical duty of 2-nurse verification
• Bariatric surgery trend → lifelong B₁₂ supplementation; informed consent must cover this

Quick Mnemonics

• Type I = "IgE – Immediate" (Anaphylaxis, Allergic rhinitis, Atopic D.)
• Type II = "Cy-2-toxic" (Transfusion reaction)
• Type III = "Immune-complex III FLOWS free" (Serum sickness)
• Type IV = "4 for Delayed Door" (Contact Dermatitis, Latex, graft rejection)