HYPERSENSITIVITY REACTIONS Flashcards
- normal but exaggerated or uncontrolled immune response to an antigen
- Can produce inflammation, cell destruction, or tissue injury
Hypersensitivity
1967: _____ was discovered which can be specific for hundreds of different allergens
IgE
any altered reaction to external substances
Allergy
refers to immediate hypersensitivity mediated by IgE antibodies
Atopy
Ag that trigger allergic reactions
Allergens
HYPERSENSITIVITY OF REACTION..
Reaction: Anaphylactic
Antibody: IgE
Complement Involved: No
Cells involved: Mast cells, basophils, granules
Cytokines involved: Yes
Comparative description: Antibody mediated, immediate
Mechanism of tissue injury: Allergic and anaphylactic reactions
Examples: Anaphylaxis, Hay Fever, Asthma, Food Allergy
Type 1
Reaction: Cytoxic
Antibody: IgG, possibly other immunoglobulins
Complement Involved: Yes
Cells involved: Effector cells (macrophages, polymorphonuclear leukocytes)
Cytokines involved: No
Comparative description: Antibody dependent: complement or cell mediated
Mechanism of tissue injury: Target cell lysis; cell-mediated cytotoxicity
Examples: Transfusion reactions, Hemolytic disease of newborn, Thrombocytopenia
Type II
Reaction: Immune complex
Antibody: Antigen-antibody complexes (IgG, IgM)
Complement Involved: Yes
Cells involved: Macrophages, Mast Cells
Cytokines involved: Yes
Comparative description: Immune complex mediated (immune complex disease)
Mechanism of tissue injury: Immune complex deposition, inflammation
Examples: Arthus reaction, Serum sickness, Systemic lupus erythematosus
Type III
Reaction: T cell-dependent
Antibody: None
Complement Involved: No
Cells involved: Antigen-specific T cells
Cytokines involved: Yes (T cell cytokines)
Comparative description: T cell-mediated, delayed type
Mechanism of tissue injury: Inflammation, cellular infiltration
Examples: Allergy or infection, Contact dermatitis
Type IV
TYPE 1 REACTIONS…
life threatening ________
anaphylactic reactions
TYPE 1 REACTIONS…
allergies
food allergies
TYPE 1 REACTIONS…
Demonstrates a ___________ tendency
strong familial or genetic
TYPE 1 REACTIONS…
acute allergic reactions caused by molecules released by mast cells/basophils when an allergen interacts with membrane-bound IgE
Immediate hypersensitivity
Acute allergic reactions result from the release of _______, _______, _______, and _______ when an allergen interacts with IgE that is bound to mast cells or basophils
preformed granule-associated mediators, membrane-derived lipids, cytokines, and chemokines
granules contain a complex of heparin, histamine, and zinc ions
mast cells
Histamine, leukotriene C4, IL-4, and IL-13 major mediators of allergy and asthma which are all formed by ____ which are release quantities after stimulation with _______
Basophils ; IL-3
IL-3 strongly induces messenger ribonucleic acid (mRNA) for _______, a major effector of granule-mediated cytotoxicity.
granzyme B
clinical response to immunologic formation and fixation between a specific antigen and a tissue-fixing antibody.
Anaphylaxis
anaphylaxis is mediated _____ antibody
IgE
clinically similar to anaphylaxis and can result from immunologically inert materials that activate serum and tissue proteases and the alternate pathway of the complement system.
Anaphylactoid reactions (anaphylaxis like):
Anaphylactoid reactions are not mediated by __________; instead, offending substances act directly on the _______
antigen-antibody interaction ; mast cells
exposure (skin, nose, or airway) to an allergen produces allergen-specific IgG antibodies
Atopic Reaction
hallmark of allergic disease (Atopic Reaction)
infiltration of affected tissue by Th2 cells
Type I Reactions: Signs & Symptoms
Localized Reaction
Generalized Reaction
occurs as an immediate response to mediators released from mast cell degranulation
Localized Reaction
Local reactions can consist of _____ and ______ at the site of antigen exposure or angioedema of the bowel after ingestion of certain foods.
urticaria and angioedema
Skin reactions are characterized be the appearance of ____ and ____ at the site of the introduction of the allergen. This phenomenon is the _____ of the skin test to diagnose an allergy or confirm sensitivity to a specific antigen.
redness and itching; basic principle
produced by mediators (cytokines and vasoactive amines (e.g., histamine)) from mast cells
Generalized Reaction
Anaphylactic reactions in generalized reaction are ____ in onset (also dramatic)
rapid
______ release leads to constriction of bronchial smooth muscle, edema of the trachea and larynx, and stimulation of smooth muscle in the GI tract (causes vomiting and diarrhea).
Histamine
In generalized reaction, the resulting breakdown of cutaneous vascular integrity results in ________ and ______; _____ causes a reduction of circulating blood volume and a progressive fall in blood pressure, leading to shock.
urticaria and angioedema ; vasodilation
Progression of allergic disease experienced by atopic children
Allergy March
In allergy march the formation of IgE antibodies begins _____
early in life
TYPE 1 REACTIONS TESTING
SKIN TESTING
PATCH TEST
IMMUNOCAP
- performed by a skin puncture test (SPT)
- assist in the identification of foods that may provoke IgE-mediated, food-induced allergic reactions or a patch test.
- cannot be considered diagnostic of FA
Skin Testing
in skin testing, placing a drop of a solution containing a possible allergen on the skin. Then a series of ______ or _____ allows the solution to enter the skin.
scratches or needle pricks
positive reaction in skin testing
red, raised and itchy area on the skin
used for the evaluation of contact food allergiesv
patch test
patch test is used to detect ________
contact dermatitis
In patch test, taping a patch that has been soaked in the allergen solution to the skin for _______
24 to 72 hours.
in vitro quantitative measurement of IgE in human serum
ImmunoCAP
considered to be the gold standard for the analysis of allergen- specific IgE.
ImmunoCAP
Antibody-Dependent, Complement-Mediated Cytotoxic Reactions
Type II Reactions
- interaction of IgG or IgM antibody with cell-bound antigen
- result in the activation of complement and destruction of the cell (cytolysis) to which the antigen is bound
Type II Reactions: Antibody-Dependent, Complement-Mediated Cytotoxic Reactions
refers to the adverse consequences of incompatibility between patient and donor erythrocytes.
Transfusion Reactions
most common cause of immediate hemolytic reactions
transfusion of ABO group–incompatible blood
most serious and potentially lethal transfusion reactions
Immediate Hemolytic Reactions
In Immediate Hemolytic Reactions, reactions can occur with the infusion of as little as ________ of incompatible blood
10 to 15 mL
Immediate Hemolytic Reactions, occur during _____ or immediately after blood has been ____
infusion ; infused
Immediate Hemolytic Reactions demonstrate _____ and ____ hemolysis
extravascular and intravascular hemolysis
delayed hemolytic reaction manifests ____ days after transfusion
7 to 10 days
delayed hemolytic reaction occurs in the _____ spaces
extravascular spaces
In delayed hemolytic reaction, ________; does not activate complement or activates it very slowly, ______ occurs
IgG antibody–coated erythrocytes ; extravascular hemolysis
from excessive destruction of fetal RBCs by maternal antibodies
Hemolytic Disease of the Fetus and Newborn
Hemolytic Disease of the Fetus and Newborn is characterized by ____ and _____
anemia and jaundice
In HDFN, most frequent form of ABO incompatibility occurs when the mother is type ____ and the baby is type __ or type __, usually type ____
O ; A or B ; A.
directed against self antigens on RBCs
Autoimmune Hemolytic Anemia
Cold autoagglutinins (IgM) react best at room temperature or lower.
Cold Autoimmune Hemolytic Anemia.
warm autoagglutinins (IgG) represent most cases of autoimmune hemolytic anemia
Warm Autoimmune Hemolytic Anemia
In Autoimmune Hemolytic Anemia, source of antigen exposure may be _____, antibodies can be formed to _____ or _____
unknown ; microorganisms or drugs
Autoimmune Hemolytic Anemia reacts best at ____ temperature
37 degree celsius
Autoantibodies can attack and damage components of solid tissues, as in _________.
Goodpasture’s syndrome
In Goodpasture’s syndrome, ___ autoantibodies bind a glycoprotein in the ______ of the kidney’s glomeruli and the lungs
IgG ; basement membrane
___________ activates complement that can trigger an inflammatory response.
Anti–basement membrane antibody
Type II Hypersensitivity and Antibodies That Affect Cell Function
- antibodies bind to cells and affect their function
- stimulate the target organ function without causing organ damage.
- Wegener’s granulomatosis: stimulation of cells by autoantibody leads to tissue damage
stimulation of cells by autoantibody leads to tissue damagev
Wegener’s granulomatosis
performed to detect transfusion reactions, HDFN, and autoimmune hemolytic anemia
direct antiglobulin test (DAT)
In DAT, If there is an __________ caused by IgM, only the C3d assay would be positive.
autoimmune hemolytic anemia
used to determine the presence of an unexpected antibody
indirect AHG assay
Goodpasture’s syndrome can be diagnosed by finding antibodies to glomerular basement membrane in patient serum on _______ or ______ examination of a _____ biopsy
indirect immunofluorescence or direct fluorescent ; renal tissue
caused by the deposition of immune complexes in blood vessel walls and tissues (repeated exposure)
Type III Reactions
Repeated antigen exposure leads to _______ with the production of an ____________.
sensitization ; insoluble antigen-antibody complex
As these complexes (insoluble antigen-antibody complex) are deposited in tissues, the complement system is _____, macrophages and leukocytes are _____, and _________ occurs.
activated ; attracted ; immune-mediated damage
skin conditions in type III reactions
allergic vasculitis; erythema nodosum
Pulmonary reactions
Farmer’s Lung
Bathtub Refinisher’s Lung
Epoxy Resin Lung
Plastic Worker’s Lung
hypersensitivity pneumonitis which is a reaction to thermophilic actinomycetes found in moldy hay
farmer’s lung
Toluene diisocyanate cause ________
bathtub refinisher’s lung
phthalic anhydride causes ________
epoxy resin lung
trimetallic anhydride causes _________
plastic worker’s lung
local immune complex diseases in type III reactions
Farmer’s lung, Arthus reaction
circulating immune complex disease in type III reactions ______
Poststreptococcal glomerulonephritis; SLE
other reactions that may occur in type III reactios
Serum Sickness
Immune complexes (in type III reactions) usually cleared by mechanisms involving _____
complement
Type III reactions are caused by ____, ____ and possibly other antibody types.
IgG, IgM
_________ develops within 1 to 2 weeks after initial exposure or repeated exposure by injection of heterologous serum protein
Acute serum sickness
hallmark of serum sickness
protracted interaction between antigen and antibody in the circulation, with the formation of antigen-antibody complexes in an environment of antigen excess.
autoimmune disorder characterized by autoantibodies that form immune complexes with autoantigens
SLE
SLE is deposited in the _________
renal glomeruli
In SLE, _____ (inflammation of capillary vessels in the glomeruli) develops.
glomerulonephritis
inflammation of capillary vessels in the glomeruli
glomerulonephritis
Type III Reactions: Testing
______ of tissue biopsy specimens can be used to observe the deposition of immune complexes in tissues
Fluorescent staining
quantitation of complement (____ and ____ components) is also a Type III Reactions Testing
C3 and C4
moderated by the link between T lymphocytes and phagocytic cells
Type IV Cell-Mediated Reactions
involves antigen-sensitized T cells or particles that remain phagocytized in a macrophage and are encountered by previously activated T cells for a second or subsequent time
Delayed-type hypersensitivity
in Delayed-type hypersensitivity…
T cells respond _____, or by the release of______, to exhibit _______ and ________
directly ; lymphokine ; contact dermatitis and allergies of infection
in Delayed-type hypersensitivity…
immunologic mechanisms ________
contact sensitivity
in Delayed-type hypersensitivity…
Rejection of ________
foreign tissue grafts
in Delayed-type hypersensitivity…
elimination of tumor cells bearing _______
neoantigens
____ can be a physiologic reaction to pathogens that are difficult to clear, such as _____ and _____. This triggers the most extreme _____
DTH ; hepatitis B virus and Mycobacterium tuberculosis ; DTH reactions
DTH reactions also take place against _______. In insulin-dependent (type 1) diabetes, T cells respond to ________, damaging the islets and eventually preventing insulin secretion.
autoantigens ; pancreatic islet cell antigens
________ is secreted by macrophages and T cells and stimulates much of the damage in DTH reactions.
Tumor necrosis factor-α (TNF-α)
The hallmark of occupational type IV hypersensitivity is
_____ caused by _____
allergic contact dermatitis ; metals
Latex contains low-molecular-weight soluble proteins that cause IgE-mediated allergic reactions
Latex Sensitivity
- Latex allergy can give rise to a broad range of symptoms. Glove wearers may experience _____ or _____, contact dermatitis that ranges from nonspecific pruritus to _____, _____, _____.
- These symptoms and the irritant contact dermatitis are caused by the _______ and _______ used in glove manufacturing, not by the latex itself.
- type IV, or delayed hypersensitivity ; nonspecific pruritus ; eczematous, red, weepy skin.
- accelerators and chemicals
skin test for testing of exposure to tuberculosis (TB) is a classic example of a _________
delayed hypersensitivity reaction
Testing for Delayed Hypersensitivity..
small amount of antigen is injected under the skin (intradermally) with a fine-needle syringe. Site is observed at ____ and. _____ hours for the presence of _____ (lesion ≥10 mm in diameter)
48 and 72 ; induration
The test is based on the principle that soluble antigens from M. tuberculosis induce a reaction in individuals who have acquired or been exposed to the tuberculosis microorganism or a related organism at some time but It does not mean that _____
the person has tuberculosis.
In cases of persistent dermatitis, a ______ may be performed. An _____ containing the suspected allergen is applied to the skin. The skin is checked for redness with ____ or _____, indicating a positive test result, over _____.
patch test ; adhesive patch ; papules or tiny blisters ; 48 hours
