HYPERSENSITIVITY REACTIONS Flashcards by Sharmaine Madjid

normal but exaggerated or uncontrolled immune response to an antigen
Can produce inflammation, cell destruction, or tissue injury

Hypersensitivity

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1967: _____ was discovered which can be specific for hundreds of different allergens

IgE

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any altered reaction to external substances

Allergy

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refers to immediate hypersensitivity mediated by IgE antibodies

Atopy

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Ag that trigger allergic reactions

Allergens

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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

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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

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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

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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

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TYPE 1 REACTIONS…

life threatening ________

anaphylactic reactions

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TYPE 1 REACTIONS…

allergies

food allergies

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TYPE 1 REACTIONS…

Demonstrates a ___________ tendency

strong familial or genetic

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TYPE 1 REACTIONS…

acute allergic reactions caused by molecules released by mast cells/basophils when an allergen interacts with membrane-bound IgE

Immediate hypersensitivity

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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

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granules contain a complex of heparin, histamine, and zinc ions

mast cells

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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

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IL-3 strongly induces messenger ribonucleic acid (mRNA) for _______, a major effector of granule-mediated cytotoxicity.

granzyme B

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clinical response to immunologic formation and fixation between a specific antigen and a tissue-fixing antibody.

Anaphylaxis

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anaphylaxis is mediated _____ antibody

IgE

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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):

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Anaphylactoid reactions are not mediated by __________; instead, offending substances act directly on the _______

antigen-antibody interaction ; mast cells

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exposure (skin, nose, or airway) to an allergen produces allergen-specific IgG antibodies

Atopic Reaction

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hallmark of allergic disease (Atopic Reaction)

infiltration of affected tissue by Th2 cells

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Type I Reactions: Signs & Symptoms

Localized Reaction
Generalized Reaction

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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

HYPERSENSITIVITY REACTIONS Flashcards

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