4.5 Autoimmune and Hypersensitivity Reactions
The body’s inflammatory and immune responses are essential defense mechanisms designed to protect us against various threats, such as infections and cancer. These responses involve activation of immune cells, release of signaling molecules, and initiation of inflammatory processes to help eliminate harmful invaders and promote tissue repair.
There are instances when an individual’s immune system becomes overly reactive, resulting in an excessive or prolonged inflammatory response that occurs at an inappropriate time or against harmless substances. This kind of exaggerated reaction can damage normal tissues and cause a range of health issues. Such responses are referred to as hypersensitivity reactions or allergic responses.
Hypersensitivity Reactions
Hypersensitivities reflect a range of exaggerated immune responses triggered by exposure to specific antigens.[1] These immune reactions can vary widely in their intensity, causing a range of effects that span from discomfort to severe and life-threatening conditions. When the immune system perceives an antigen as a threat, it can lead to a heightened and often disproportionate response.
Allergic responses are a specific type of hypersensitivity reactions that arise when the immune system reacts to allergens, substances that are generally harmless to most individuals.[2] Common allergens include pollen, dust mites, pet dander, certain foods, and insect venom. When a person with allergies encounters these allergens, their immune system goes into overdrive, releasing histamines and other inflammatory molecules that trigger symptoms such as itching, sneezing, wheezing, hives, or in severe cases, anaphylactic shock. See Table 4.5 for a summary of hypersensitivity reactions.[3],[4]
Table 4.5. Hypersensitivity Reactions
| Hypersensitivity Type | Description | Mechanism | Examples | Nursing Interventions |
|---|---|---|---|---|
| Type 1 Hypersensitivity (Immediate) | Also known as atopic allergy; this is the most common type of hypersensitivity reaction. It involves rapid and excessive immune responses to harmless antigens (allergens) that lead to allergic reactions. | Upon initial exposure, sensitization occurs, involving the production of IgE antibodies against the allergen. Upon subsequent exposure, the allergen binds to IgE antibodies on mast cells and basophils, triggering the release of inflammatory mediators like histamine. | Inhaled allergens (pollens, animal dander), ingested allergens (foods, drugs), injected allergens (bee venom, drugs), and contacted allergens (latex, environmental proteins).
Anaphylactic reactions can occur, involving widespread blood vessel dilation, decreased cardiac output, and bronchoconstriction. |
Provide antihistamines and corticosteroids as prescribed, administer epinephrine for anaphylactic reactions, and educate clients about allergen avoidance. |
| Type 2 Hypersensitivity (Cytotoxic) | This type involves antibodies targeting antigens on cell surfaces, leading to the destruction or dysfunction of the affected cells. | Antibodies (IgG, IgM) bind to antigens on cell surfaces, triggering immune-mediated destruction through complement activation or antibody-dependent cell-mediated cytotoxicity. | Hemolytic transfusion reactions, autoimmune hemolytic anemia, and drug-induced cytotoxic reactions. | Monitor for signs of hemolysis, administer blood product transfusions as needed, implement plasmapheresis as prescribed, and provide supportive care. |
| Type 3 Hypersensitivity (Immune Complex) | Immune complexes formed between antibodies and soluble antigens deposit in various tissues, leading to localized inflammation and tissue damage. | Immune complexes attract neutrophils, causing inflammation and tissue damage at the site of deposition. | Post-streptococcal glomerulonephritis, serum sickness, systemic lupus erythematosus, and rheumatoid arthritis. | Administer anti-inflammatory medications, monitor for signs of tissue damage, provide pain relief, and educate clients on self-care. |
| Type 4 Hypersensitivity (Delayed) | This type involves cell-mediated immune responses mediated by T cells, causing inflammation and tissue damage. | Sensitized T cells recognize antigens presented by antigen-presenting cells, releasing cytokines that recruit inflammatory cells and induce tissue damage. | Contact dermatitis, tuberculin skin test reactions, and graft rejection. | Administer corticosteroids for severe reactions, provide wound care for dermatitis, and monitor graft sites for signs of rejection. |
| Type 5 - Stimulated (Autoimmune Reaction) | The immune system mistakenly attacks the body’s own cells and tissues as if they were foreign antigens, leading to chronic inflammation and tissue damage. | Autoantibodies and autoreactive T cells target self-antigens, causing immune-mediated damage to various tissues and organs. | Rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, and type 1 diabetes. | Administer immunosuppressive medications, manage symptoms, provide emotional support, and educate clients on self-management. |
Read more about “Rheumatoid Arthritis” in the “Musculoskeletal Alterations” chapter, “Diabetes Mellitus” in the “Endocrine Alterations” chapter, “Multiple Sclerosis” in the Nervous System Alterations chapter, and “Systemic Lupus Erythematosus” later in this chapter.
Anaphylaxis
Anaphylaxis is a Type I hypersensitivity reaction that occurs rapidly and systemically, and if not promptly treated, it can be fatal. It involves a severe and often sudden immune response triggered by the release of inflammatory mediators in response to an allergen. During an anaphylactic reaction, the body experiences a cascade of symptoms that can affect multiple systems.
Clients experiencing anaphylaxis can have various signs and symptoms. They may experience feelings of uneasiness, apprehension, or a sense of impending doom. Generalized itching and urticaria (hives) can manifest as raised, red, and itchy skin lesions. Erythema and angioedema, characterized by localized swelling often around the eyes, lips, and throat, may occur. Additionally, congestion and rhinorrhea (runny nose) may occur, leading to dyspnea (difficulty breathing) and respiratory distress. In severe cases, anaphylaxis can cause bronchoconstriction and swelling of the throat, leading to obstruction of the airway, a potentially life-threatening condition. Recognition of symptoms and signs of anaphylaxis and prompt intervention are crucial. Treatment typically involves the administration of epinephrine to counteract the systemic effects of anaphylaxis and stabilize the client’s condition.[5],[6]
Interventions for treating anaphylaxis are outlined in the following box.
Interventions for Anaphylaxis[7],[8]:
- Assess respiratory function to monitor for signs of airway obstruction or distress.
- Establish or stabilize the airway if necessary to ensure proper breathing and oxygenation.
- Provide supplemental oxygen to maintain adequate oxygen saturation levels.
- Stay with the client to provide continuous monitoring and support.
- Administer epinephrine (1:1000) as the first-line drug for anaphylaxis; the recommended dose is 0.3-0.5 mL, usually given intramuscularly in the thigh. Epinephrine helps counteract the severe effects of the allergic reaction by increasing heart rate, improving breathing, and reducing blood vessel dilation.
- Administer antihistamines to help relieve itching, hives, and other allergic symptoms.
- Administer a beta-adrenergic agonist (such as albuterol) to help relax bronchial smooth muscles and alleviate bronchoconstriction.
- Administer corticosteroids, either intravenously or orally, to help reduce inflammation and prevent delayed allergic reactions.
- Continuously monitor the client’s vital signs, respiratory status, and overall response to interventions.
- Prepare for potential additional interventions, such as intravenous fluids, if the client’s condition warrants it.
- Provide education and support to the client and family regarding anaphylaxis triggers, emergency action plans, and the proper use of epinephrine auto-injectors if applicable.
RN Recap: Type 1 Hypersensitivity (Immediate) Reaction
View a supplementary YouTube video[9] overview of Type 1 Hypersensitivity (Immediate) Reaction:
RN Recap: Type 2 Hypersensitivity (Cytotoxic) Reaction
View a supplementary YouTube video[10] overview of Type 2 Hypersensitivity (Cytotoxic) Reaction:
- Immunodeficiency UK. (2018, April). Allergy and hypersensitivity. https://www.immunodeficiencyuk.org/ ↵
- Immunodeficiency UK. (2018, April). Allergy and hypersensitivity. https://www.immunodeficiencyuk.org/ ↵
- Immunodeficiency UK. (2018, April). Allergy and hypersensitivity. https://www.immunodeficiencyuk.org/ ↵
- This work is a derivative of StatPearls by Vailliant, Vashist, & Zito and is licensed under CC BY 4.0 ↵
- Immunodeficiency UK. (2018, April). Allergy and hypersensitivity. https://www.immunodeficiencyuk.org/ ↵
- This work is a derivative of StatPearls by Vailliant, Vashist, & Zito and is licensed under CC BY 4.0 ↵
- Immunodeficiency UK. (2018, April). Allergy and hypersensitivity. https://www.immunodeficiencyuk.org/ ↵
- This work is a derivative of StatPearls by Vailliant, Vashist, & Zito and is licensed under CC BY 4.0 ↵
- Open RN Project. (2024, March 25). Health Alterations - Chapter 4 Malignancy - Type 1 Immediate Hypersensitivity Reaction. [Video]. YouTube. CC BY-NC 4.0 https://www.youtube.com/watch?v=KQj7aHVem-0 ↵
- Open RN Project. (2024, March 25).Health Alterations - Chapter 4 Malignancy - Type 2 Cytotoxic Reaction.[Video]. YouTube. CC BY-NC 4.0 https://www.youtube.com/watch?v=mlkTixljv-0 ↵
A range of exaggerated immune responses triggered by exposure to specific antigens.
A specific type of hypersensitivity reactions that arise when the immune system reacts to allergens, substances that are generally harmless to most individuals.
Substances that are generally harmless to most individuals.
The most common type of hypersensitivity reaction that involves rapid and excessive immune responses to harmless allergens.
A hypersensitivity reaction that involves antibodies targeting antigens on cell surfaces, leading to the destruction or dysfunction of the affected cells.
A hypersensitivity reaction that involves immune complexes formed between antibodies and soluble antigens that deposit in various tissues, leading to localized inflammation and tissue damage.
A hypersensitivity reaction that involves cell-mediated immune responses mediated by T cells, causing inflammation and tissue damage.
A hypersensitivity reaction that occurs when the immune system mistakenly attacks the body's own cells and tissues as if they were foreign antigens, leading to chronic inflammation and tissue damage.
A life-threatening type I hypersensitivity reaction that occurs rapidly and systemically, and if not promptly treated, it can be fatal.
