Allergy Flashcards
- Define Allergy.
A specific type of immune response elicited by exposure to an antigen - hypersensitivity (medical term for allergy).
- Define antigen.
A substance that can generate an immune response.
- What are the key cells of the Type I hypersensitivity reaction and what do they do?
B-cell makes the IgE, and mast cells release mediators
- What do the heavy chains of the antibody determine?
What type of antibody it is, IgG, IgA, IgE, IgD, or IgM
- What do the light chains of the antibody determine?
The light chain portion couples with the heavy chain portion to form the antigen binding site
- What are the histologic consequences of mast cell degeneration?
Edema, vascular congestion and vasodilation, increased vascular permeability
- What cells denote a late phase Type I hypersensitivity reaction?
Eosinophils
- What are two signs of the tissue pathology of asthma?
Goblet cell hyperplasia due to repeated stimulation of mucous secretion & smooth muscle hypertrophy due to repeated episodes of bronchoconstriction
- What is the potentially lethal manifestation of type I hypersensitivity, what causes it, and how do you treat it?
Anaphylaxis due to circulatory failure widespread vasodilation and low volume from vascular leakage and respiratory failure due to bronchoconstriction from smooth muscle contraction and airway obstruction from laryngeal edema. Epinephrine
- What causes autoimmune hemolytic anemia?
IgG bound to the surface of red blood cells, immune system is attacking red blood cells
- Antibodies should only be bound to
things we want to fight against, not the cells in our bodies.
- What determines the symptoms of antibody mediated (type II) hypersensitivity reaction?
Organ involvement, blood=cytopenias, kidney=renal failure
- What happens in antibody mediated (type II) hypersensitivity?
IgG or IgM production which bind to host tissue and causes host tissue destruction
- What do B-cells make?
B-cells are a plasma cells that make antibody (immunoglobulin)
- What is the purpose of neutrophils, natural killer cells, and the complement system?
They destroy the cells and tissue that is labeled by the antibody (and cause collateral damage to surrounding tissue)
- What are the three mechanisms of destroying cells labeled with antibody?
Opsonization and phagocytosis, antibody-dependent cell-mediated cytotoxicity, and complement mediated cell lysis
- What do natural killer cells contain?
Cytotoxic granules
- What is the purpose of the MAC complex in this process? Label it on your drawing. Punches a hole in the cell which causes cell lysis
Label it on your drawing. Punches a hole in the cell which causes cell lysis
- Explain the pathophysiology of Goodpasture syndrome.
Type II hypersensitivity. Autoimmune disorder where Auto-antibodies bind proteins in the basement membrane of the lung and kidney, which causes respiratory and renal failure do to compromise of air exchange and filtration capacities
- What denotes Type III hypersensitivity?
Immune complex formations
- What are the most common clinical presentations of systemic lupus erythromatosis?
Anemia and prescence of anti-nuclear antibodies (ANA), arthritis, and mallar “butterfly” rash
- What does an elevated ANA mean?
Fragments of nuclei are circulating because cells are dying and sometimes antibodies develop against these
- What are immune complexes? Draw it.
Antibodiess form against the nuclear proteins, these antibodies deposit in the blood vessels of the targeted organs, these deposited immune complexes stimulate tissue destruction.
- What is the end result immune complex release?
Chronic inflammation and tissue death
- How long does it take T-cells to develop a response?
24-2hrs
- What type of hypersensitivity reaction are T-cells responsible for?
Type IV, cell mediated
- Granuloma formation is indicative of what type of hypersensitivity reaction? Purpose?
Type IV, cell mediated. The purpose of granulomas is to isolate and contain the infection.
- What type of infections are people deficient in T-cells most susceptible to?
Fungal, viral, malignacies
What is a histamine?
Potent biologically active mediator. released by mast cells
What is type I (immediate) hypersensitivity?
IgE antibody production, Mast cell degranulation, and release of mediators
Disease: allergies, anaphylaxis, asthma
Hay fever, runny nose, edema wheezing, coughing.
Whats another word for immunoglobulin?
Antibody
What happens to goblet cells and smooth muscle with asthma?
Goblet cell hyperplasia due to repeated stimulation for mucous secretion
Smooth muscle hypertrophy due to repeated episodes of bronchoconstriction
What is anaphylaxis?
Potentially lethal manifestation of immediate hypersensitivity (TYPE I)
- Circulatory failure: Hypotension due to vasodilation and low circulating volume (vascular leakage – edema)
- Respiratory failure: Bronchoconstriction from smooth muscle contraction and airway obstruction from laryngeal edema
• Treatment = epinephrine
What is Type II (antibody mediated) hypersensitivity
Production of IgG, IgM
Antibody binds antigen
Phagocytosis or cell lysis
Diseases:
– Autoimmune hemolytic anemia
– Goodpasture syndrome Symptoms:
– Dependent upon organ involvement
Blood = cytopenias Kidney = renal failure
Goodpasture syndrome
Auto antibodies bind proteins in the basement membranes of lung and kidney
Type III IMMUNE COMPLEX mediated hypersensitivity
These immune complexes can be deposited on blood vessel walls and in tissues. When this occurs, injury to the vessel walls and tissues may ensue because of thrombosis and complement activation.
Example would be systemic lupus erythematosus. the antibodies are directed against a variety of antigens found within the nucleus of our own cells.
Immune complex formation (circulating globs of antibody
bound to antigen)
Immune complex deposits in small blood vessels (skin = rash,
joints = arthritis, etc)
Deposited immune complex stimulate local inflammation and
tissue destruction
Key cells:
– B‐cell (plasma cell) = makes antibody (immunoglobulin)
– Neutrophils and other inflammatory c
Cell Mediated (Type IV) hypersensitivity
Initiated by T-cells and is also called delayed type.
T‐cells are activated by fungi, mycobacteria, or foreign material (eg. Talc)
- Activated T‐cells then activate macrophages, causing macrophages to enlarge and group together into a structure called a granuloma
- Granulomas isolate and contain infections or foreign bodies
Best way to explain cell mediated hypersensitivity is through the tb skin test. In patients with prior sensitization (exposure) to TB, red induration (swelling ) will be noted.. T cells primed against foreign antigens can orchestrate an immune response against anything that displays the antigen.
What would cause a T cell deficiency?
HIV, fungal infections, viral infections
T/F: Anaphylaxis is primarily mediated by B-Cells.
F
What is a disease characterized by numerous granulomas, especially in the lungs due to excessive cell mediated hypersensitivity
TB and Sarcoidosis
T/F: Immune complexes cause injury to blood vessels and tissues by inducing thrombosis and activating complement.
T
T/F: cells are primarily responsible for cell mediated hypersensitivity
T
