Term
hypersensitivity definition
ATOPIC |
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Definition
= to allergy = exaggerated immune responses/reactivity
1. it exceeds healthy limits of intensity and/or
2. it is directed at tissues that are sensitive to the products of such responsiveness/reactivity
highly allergic patients termed (blank) |
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Term
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Definition
harmless antigen
stimulates (blank) responses in atopic individual
particularly used in reference to antigens responsible for IgE associated allergy |
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Term
sensitization vs. elicitation
sensitization
elicitization |
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Definition
hypersensitivity diseases require initial (blank) to then be (blanked) against
(blank) phase may be completed before antigen is cleared from the body - (blank) can then happen during initial allergen exposure, but usually happens after second exposure to allergen |
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Term
immune response vs. immune reaction
immune response |
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Definition
sensitization can be required to involve an (blank) (blank) in hypersensitivity diseases
these initial (blank) (blank)s could produce potentially harmful soluble or cellular factors
(blank) (blank)s happen when these responses CAUSE damage to host tissues - it is the effect of above
time frame between immune response and immune reaction (pathology) may vary |
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Term
| list types of hypersensitivity |
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Definition
Type I - immediate hypersensitivity (IgE antibody)
Type II -cytotoxic antibody (target cell-specific IgG)
Type III - immune complex disease (IgG binds antigen big time and causes insoluble antibody-antigen complexes to form)
Type IV - Delayed-type (effector T cells/macs attack antigen-coated host cells) |
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Term
| Type I (Immediate) Hypersensitivity |
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Definition
| sensitization - TRANSMUCOSAL exposure, IgE antibody production; IgE bound to Fc-epsilon-R on mast cells/basophils elicitation (minutes) - second allergen exposure; allergen binds IgE "fixed" to mast cell; crosslinking and degranulation; release of pharmacologically active factors |
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Term
| Type I hypersensitivity - sensitization |
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Definition
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Term
| type I hypersensitivity - elicitation |
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Definition
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Term
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Definition
minor localized irritations
happens in nasopharynx and upper airway in type I hypersensitivity |
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Term
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Definition
serious localized allergic reaction
happens in submucosa of lower airways in type I hypersensitivity |
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Term
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Definition
| life-threatening SYSTEMIC circulatory collapse |
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Term
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Definition
mast cells, when stimulated in type I hypersensitivity (remember, IgE hooked on to mast cells via Fc-epsilonRI and bind antigen)
in this process, granules that are let out of mast cells and basophils contain anyanplyotoxins that increase vascular permeability, increased blood flow, decreased blood pressure, increased mucous secretions and smooth m contraction
bridging of IgE molecules and mast cell causes influx of calcium into mast cell that results in DECREASED CYLCIC AMP
this causes destabilization of membrane
influx of calcium also results in MEMBRANE LIPID TURNOVER yielding via ARACHIDONIC ACID, LUEKOTRIENES and PROSTAGLANDINS |
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Term
| examples of products released by degranulation |
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Definition
histamine (^ vas perm and local blood flow)
leukotrienes and prostaglandins (sm m. contraction and ^ vas perm)
chemokines (attract leukocytes)
enzymes (break down tissue matrix proteins)
cytokines (promote inflammatory activities, amp of TH2 responses, ^ growth of eosinophils) |
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Term
wheal-and-flare reactions
urticaria (hives)
Urticaria (hives) |
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Definition
skin reaction in type I HS
follows local intracutaneous exposure to allergen (such as insect bite)
skin tests for antigen-specific IgE hypersensitivity mimic and measure this type of localized reaction
in a related condition called (blank) - allergin is ingested, but then migrates to the skin |
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Term
| treatments of type I HS (4) |
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Definition
Avoidance
Desensitization - small to large doses changes IgE-dominated responses to IgG that doesn't bind well to mast cells
inhibition of mediator release - designed to either inhibit calcium or raise levels of cAMP
inhibition of mediator effects - administer epinephrine (reverse effect of anaphylotoxins), inhalation of bronchodialators and antihistamines (H receptor antagonists)..... inflammation can be treated with corticosteroids |
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Term
| common symptoms of type I HS |
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Definition
allergic rhinitis
allergic asthma (S.O.B.)
venom reactions
food allergies
drug allergies
urticaria (hives)
anaphylactic shock |
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Term
| describe sensitization of type II hypersensitivity |
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Definition
| antibodies made that are specific to EXTRINSIC (foreign) ANTIGENS or reactive with INTRINSIC ANTIGENS (produced by target tissue itself |
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Term
| describe elicitation of type II HS |
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Definition
time of onset varies
symptoms caused by binding of antigen-reactive antibody (IgG usually) specifically to ANTIGEN-COATED HOST CELLS; followed by direct lysis due to complement activation and further aggravated by release of active by-products of complement cascade (anaphylatoxins C3a, C5a)
FcR-bearing and CR-bearing leukocytes are also recruited to the area |
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Term
| what distinguishes type II (cytotoxic antibody) from type III (immune complex) in the biopsy? |
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Definition
| type II will demonstrate SMOOTH layer of antibody/complement coating host tissue |
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Term
| two examples of type II (cytotoxic antibody) HS |
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Definition
Hemolytic Disease of the Newborn (HDN) - mom is Rh(neg) and fetus is Rh(pos); mom is sensitized after first Rh(pos) birth; next pregnancy, she elicits type II HS to Rh(pos) antigens in fetus (IgG antibodies can cross into placenta); causes SEVERE ANEMIA in fetus; RhoGam can be used to avoid these complications
Goodpasture's Syndrome - antibodies produced that attack BASEMENT MEMBRANES of renal glomeruli and (in some cases) pulmonary alveoli; binding occurs specifically to alpha-3 chain of type IV collagen of BM |
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Term
| goodpasture's syndrome... tell me about it |
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Definition
type II (cytotoxic antibody) HS
antibodies produced that attack BASEMENT MEMBRANES of renal glomeruli and (in some cases) pulmonary alveoli;
binding occurs specifically to alpha-3 chain of type IV collagen of BM |
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Term
| hemolytic disease of the newborn |
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Definition
mom is Rh(neg) and fetus is Rh(pos);
mom is sensitized after first Rh(pos) birth; next pregnancy, she elicits type II HS to Rh(pos) antigens in fetus (IgG antibodies can cross into placenta);
causes SEVERE ANEMIA in fetus;
RhoGam can be used to avoid these complications |
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Term
| describe sensitization in type III HS (immune complex disease) |
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Definition
initial antigen exposure = activation of antigen-specific B cells
specific IgG antibodies reactive with antigen; antigen is soluble and freely circulating |
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Term
| describe elicitation in type III HS (immune complex disease) |
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Definition
no need for additional antigen exposures! this response is direct
many molecules of antibody bind to many molecules of antigen forming multiple crosslinks to each other - eventually form LARGE INSOLUBLE ANTIBODY-ANTIGEN COMPLEXES
normally, phagocytes eat up these immune complexes, but this reaction builds up so fast that they can't keep up
deposition of the complexes can occur in/on filtering organs such as kidneys or areas rich in capillary beds (lungs) |
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Term
| what are symptoms of type III (immune complex disease) HS |
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Definition
** symptoms caused by non-specific deposition of immune complexes
serum sickness
farmers lung syndrome
rheumatoid arthritis
systemic lupus erythematosus |
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Term
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Definition
test of type III hypersensitivity
inject antigen into skin; if it attracts circulating IgG (forms immune complexes) then this patient has type III HS to that antigen |
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Term
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Definition
| happens when large quantities of foreign antigen are given to a patient to treat infects or intoxications (snake bite) |
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Term
| describe sensitization process of type IV hypersensitivity (delayed-type) |
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Definition
activate CD4+ TH1/TH17cells (not TH2s)
10-14 days
antigen covalently attaches to host tissue membranes - effector activities then directed against host tissues
CD8+ cells can also be activated if antigen is lipid soluble and crosses PM of host cells |
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Term
| describe elicitation process of type IV hypersensitivity (delayed-type) |
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Definition
type 4 HS (DTH) is exaggerated form of cell-mediated immunity
symptoms caused by T cell derived cytokines (chemokines, IFN-gama, TNF-alpha, TNF-beta, IL-3/GM-CSF)
nonspecific T cells
significant EDEMA and INDURATION (hardness) |
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Term
| what are the 3 different variants of DTH (delayed type hypersensitivity) |
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Definition
contact hypersensitivity - langerhans' cell is APC to T cells in EPIDERMIS; 24-48 hrs; POISON IVY
tuberculin hypersensitivty - intradermal reaction; macrophages present antigen to T cells; TB tests with purified protein derivative (PPD) of tubercule bacilli
granulomatous hypersensitivity - 21-28 days; antigens within macrophage difficult to degrade; GRANULOMA FORMATION; make multi-nucleated giant cells (from T cell cuff around a core of macs); EPITHELIOD CELLS also present inside these cuffs; size/mass of granulomas keep growing |
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Term
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Definition
langerhans' cell is APC to T cells in EPIDERMIS;
24-48 hrs;
POISON IVY |
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Term
| tuberculin hypersensitivity |
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Definition
intradermal reaction;
macrophages present antigen to T cells;
TB tests with purified protein derivative (PPD) of tubercule bacilli |
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Term
| granulomatous hypersensitivity |
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Definition
21-28 days;
antigens within macrophage difficult to degrade;
GRANULOMA FORMATION - make multi-nucleated giant cells (from T cell cuff around a core of macs);
EPITHELIOD CELLS also present inside these cuffs;
size/mass of granulomas keep growing |
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Term
type II HS
goodpasture's syndrome
alpha-3 chain
type IV collagen of basement membrane
triggers complement cascade
type II HS called CYTOTOXIC ANTIBODY hypersensitivity |
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Definition
this is an example of type (blank) HS
(blank) (blank) - antibodies produced that attack BASEMENT MEMBRANES of renal glomeruli and (in some cases) pulmonary alveoli
antibody binding triggers (blank) cascade, resulting in cell death = reason why type (blank) HS is called (blank) (blank) hypersensitivity
binding occurs specifically to (blank) chain of type (blank) collagen of (blank) |
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Term
type II HS
goodpasture's syndrome
alpha-3 chain
type IV collagen of basement membrane
triggers complement cascade
type II HS called CYTOTOXIC ANTIBODY hypersensitivity |
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Definition
this is an example of type (blank) HS
(blank) (blank) - antibodies produced that attack BASEMENT MEMBRANES of renal glomeruli and (in some cases) pulmonary alveoli
antibody binding triggers (blank) cascade, resulting in cell death = reason why type (blank) HS is called (blank) (blank) hypersensitivity
binding occurs specifically to (blank) chain of type (blank) collagen of (blank) |
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