Alterations in Immunity and Inflammation Flashcards
Inappropriate Immune Responses
Allergy: Is an exaggerated response against
an environmental antigen.
Autoimmunity: Is a misdirected response against the host’s own cells.
Alloimmunity: Is directed against beneficial foreign tissues (e.g., transfusions, transplants)
Immunodeficiency: Immunity is insufficient to protect the host.
Alloimmunity occurs when:
The immune system produces a response to tissues of another individual.
Hypersensitivity
Is an altered immunologic response to an antigen that results in disease or damage to the host.
Allergy
Produces deleterious effects of hypersensitivity to environmental (exogenous) antigens.
Autoimmunity
Is a disturbance in immunologic tolerance of self-antigens.
Can cause autoimmune diseases.
Alloimmunity
Is an immune reaction to tissues of another individual.
Is also called isoimmunity.
Three variables to Hypersensitivity
Original “insult”: Alters immunologic homeostasis, which is the steady state of tolerance to self-antigens or the lack of immune reaction against environmental antigens.
Individual’s genetic makeup: Determines the degree of the resultant immune response from the effects of the insult.
Immunologic process: Causes disease symptoms.
Type 1 (Hypersensitivity)
IgE mediated
Is against environmental antigens (allergens).
IgE binds to crystalline fragment (Fc) receptors on the surface of mast cells; cross linking causes the release of histamine from mast cell degranulation.
H1 and H2 receptors
Increases chemotactic activity
Cytotropic antibodies bind to the cell surface and reagins are antibodies that can bind to skin.
Type 2 (Hypersensitivity)
Tissue-specific reactions
Ex: Mismatched blood
Tissue specific
Specific cell or tissue (tissue-specific antigens) is the target of an immune response.
Five mechanisms
- )Cell is destroyed by antibodies and complement.
- )Cell destruction occurs through phagocytosis.
- )Neutrophils release granules.
- )Antibody-dependent cell-mediated cytotoxicity is present.
- )Causes target cell malfunction.
Type 3 (Hypersensitivity)
Immune complex mediated (kidneys are vulnerable)
Ex: Lupus (autoimmune disorder)
Complexes are formed in the circulation and deposited later in vessel walls or extravascular tissues.
Is not organ specific.
Damage results from complement activation and neutrophil lysosomal enzymes.
Immune complex clearance
Large: Macrophages
Small: Renal clearance
Intermediate: Deposited in tissues; causes problems
Type 4 (Hypersensitivity)
Cell mediated/Delayed
Ex: Transplant/ Tuberculosis/Poison Ivy
Destruction of the tissue is usually caused by direct killing by toxins from cytotoxic T (Tc) cells Helper T (Th) 1 and Th 17 cells produce cytokines that recruit phagocytes, especially macrophages.
Examples
Acute graft rejection, skin test for tuberculosis (TB), contact allergic reactions, and some autoimmune diseases, Type 1 Diabetes
Anaphylaxis (Hypersensitivity)
Anaphylaxis
Generalized: Can be life threatening
Localized: (rash/itching/airway edema)
Anaphylaxis
Severity depends on the level of sensitization.
Develops in minutes after exposure.
Itching (peritis) Erythema Headaches Contraction of respiratory bronchioles Laryngeal edema Vomiting, abdominal cramps, diarrhea Vascular collapse
Bee stings, peanuts, and fish, among others, can cause anaphylaxis.
Manifestations from Type 1 to Type 2
Type 1
Bronchial constriction
Edema
Vasodilation
Type 2
Increases gastric secretions
Decreases the release of histamine from mast cells and basophils
Immune Complex Disease
Is characterized by a variety of symptoms.
Periods of remission or exacerbation occur.
Examples
Serum sickness
Affected tissues are blood vessels, joints, and kidney.
An example is Raynaud phenomenon
Arthus reaction
Localized response causes increased vascular permeability, an accumulation of neutrophils, edema, hemorrhage, clotting, and tissue damage.
A person has a type I allergic reaction. Which pathophysiologic response is occurring?
IgE and products of tissue mast cells are released.
Systemic lupus erythematosus (SLE)
Chronic multisystem inflammatory disease
Autoantibodies against:
Nucleic acids, erythrocytes, coagulation proteins, phospholipids, lymphocytes, platelets, and many others
Deposition of circulating immune complexes containing antibody against the host’s deoxyribonucleic acid (DNA)
More common in females
Clinical manifestations of Systemic lupus erythematosus (SLE)
Arthralgias or arthritis Vasculitis and rash Renal disease Hematologic changes, especially anemia Cardiovascular disease
Eleven findings are common.
Presence of at least four findings indicates SLE.
Facial (malar) rash, discoid rash, photosensitivity, oral or nasopharyngeal ulcers, nonerosive arthritis, serositis, renal disorders, neurologic disorders, hematologic disorders, immunologic disorders, and presence of antinuclear antibodies (ANAs)
Currently, there is no cure for SLE.
