Immunology Chapter 15

Front 1

anaphylactic reactions initiated by antibody or antigen-antibody complexes

symptoms are manifest w/in minutes or hours after a sensitized recipient encounters antigen

Back 1

immediate hypersensitivity

Front 2

induce mast cell degranulation w/ release of histamine and other biologically active molecules

Back 2

IgE antibodies

Front 3

induce hypersensitivity reactions by activating complement

Back 3

IgG and IgM antibodies

Front 4

in these reactions, the effector molecules are various cytokines secreted by activated Th cells or Tc cells themselves

Back 4

delayed-type hypersensitivity

Front 5

this class of antibody secreted in a type 1 hypersensitive response bind w/ high affinity to Fc receptors

Back 5

IgE

Front 6

mast cells and basophils coated by IgE are said to be...

Back 6

sensitized

Front 7

a hereditary predisposition to the development of immediate hypersensitivity reactions against common environmental antigens

Back 7

atopy

Front 8

the majority of humans mount significant IgE responses only as a defense against...

Back 8

parasitic infections

Front 9

refers specifically to nonparasitic antigens capable of stimulating type 1 hypersensitive responses in allergic individuals on repeated exposure

Back 9

allergen

Front 10

have abnormally high levels of circulating IgE and elevated numbers of circulating eosinophils

Back 10

atopic individuals

Front 11

half-life of IgE in serum

Back 11

2-3 days

Front 12

half-life of IgE bound to its receptor on mast cells and basophils

Back 12

weeks

Front 13

two cell types which bind IgE with high affinity

Back 13

tissue mast cells
blood basophils

Front 14

unlike tissue mast cells, these cells must be recruited into tissues at the sites of inflammation

Back 14

circulating blood basophils

Front 15

ability of mast cells to adapt various phenotypes in response to their microenvironment

Back 15

mast cell heterogeneity

Front 16

high-affinity receptor constitutively expressed on mast cells and basophils

binds IgE with exceptionally high affinity

Back 16

Fc(eta)RI

Front 17

four polypeptide chains contained in Fc(eta)RI receptors on mast cells and basophils

Back 17

an alpha and beta chain and two identical disulfide-linked gamma chains

Front 18

the external region of the ____ _____ contains two domains of 90 amino acids that are homologous w/ the Ig-fold structure

Back 18

alpha chain

Front 19

one Fc(eta)RI interacts w/ both ______ domains of one IgE molecule via the two Ig-like domains of the receptor alpha chain

Back 19

Ch3

Front 20

spans the plasma membrane four times and is thought to link the alpha chain to the gamma homodimer

Back 20

beta chain

Front 21

extend a considerable distance into the cytoplasm and have the main responsibility for intracellular signal transduction

Back 21

disulfide-linked gamma chains

Front 22

binds to the CH3 domains of IgE and has a much lower affinity for IgE

Back 22

Fc(eta)RII
(or CD23)

Front 23

has a single membrane-spanning region followed by an extracellular C-type lectin domain and is structurally unrelated to Fc(eta)RI

Back 23

CD23
Fc(eta)RII

Front 24

allergen cross-linkage of IgE bound to this molecule has been shown to activate B cells, alveolar macrophages, and eosinophils

Back 24

Fc(eta)RII
CD23

Front 25

non-IgE-mediated stimuli that can also initiate the process of degranulation

Back 25

anaphylatoxins (C3a and C5a)
various drugs
other mast-cell receptors

Front 26

hydrolyzes membrane phospholipids, leading to the formation of arachidonic acid, which is converted into two classes of potent lipid mediators: prostaglandins and leukotrienes

Back 26

phospholipase A2
PLA2

Front 27

concomitant w/ phospholipid methylation and Ca2+ increase, there is a transient increase in the activity of membrane-bound adenylate cyclase, w/ a rapid peak of its reaction product, ______ ____ _______, reached about 1 minute after cross-linkage of Fc(eta)RI

Back 27

cyclic adenosine monophosphate (cAMP)

Front 28

cAMP actions

Back 28

exerted through cAMP-dependent protein kinases, which phosphorylate proteins on the granule membrane, thereby increasing the permeability of the granules to water and Ca2+

consequent swelling of the granules facilitates their fusion w/ the plasma membrane, releasing their contents

Front 29

pre-made before degranulation and are stored in the granules

most significant of this type are histamine, proteases, eosinophil chemotactic factor, neutrophil chemotactic factor, and heparin

Back 29

primary mediators

Front 30

are either synthesized after target-cell activation or released by the breakdown of membrane phospholipids during the degranulation process

include platelet-activating factor, leukotrienes, prostaglandins, bradykinins, and various cytokines and chemokines

Back 30

secondary mediators

Front 31

formed by decarboxylation of the AA histidine, major component of mast-cell granules, accounting for about 10% of granule weight

Back 31

histamine

Front 32

since it is preformed, its biological effects are observed w/in minutes of mast-cell activation

once released from mast cells, it initially binds to specific receptors on various target cells

four types of receptors exist; which have different tissue distributions and mediate different effects when they bind

Back 32

histamine

Front 33

binding of this to H1 receptors--which mediate most of the biologic effects induces:

contraction of intestinal and bronchial smooth muscles, increased permeability of venules, and increased mucus secretion by goblet cells

Back 33

histamine

Front 34

interaction of histamine with this receptor increases vasopemeability and vasodilation, stimulates endocrine glands, and increases the release of acid in the stomach

binding of histamine to this receptor on mast cells and basophils suppresses degranulation; thus, histamine exerts negative feedback on the release of mediators

Back 34

H2

Front 35

as secondary messengers, are not formed until the mast cell undergoes degranulation and the enzymatic breakdown of phospholipids in the plasma membrane

their effects take longer to become apparent, but are more pronounced and longer lasting than those of histamine

Back 35

leukotrienes and prostaglandins

Front 36

mediate bronchoconstriction, increased vascular permeability, and mucus production

secondary mediator

Back 36

leukotrienes

(prostaglandin D2 also causes brochoconstriction)

Front 37

in humans, the _____ are thought to contribute to the prolonged brochospasm and buildup of mucus seen in asthmatics

Back 37

leukotrienes

Front 38

stimulate a Th2 response and thus increase IgE production in B cells

Back 38

IL-4 and IL-13

Front 39

especially important in the recruitment and activation of eosinophils

Back 39

IL-5

Front 40

high concentrations secreted by mast cells may contribute to shock in systemic anaphylaxis

Back 40

TNF-alpha

Front 41

formed by decarboxylation of the AA histidine, major component of mast-cell granules, accounting for about 10% of granule weight

Back 41

histamine

Front 42

since it is preformed, its biological effects are observed w/in minutes of mast-cell activation

once released from mast cells, it initially binds to specific receptors on various target cells

four types of receptors exist; which have different tissue distributions and mediate different effects when they bind

Back 42

histamine

Front 43

binding of this to H1 receptors--which mediate most of the biologic effects induces:

contraction of intestinal and bronchial smooth muscles, increased permeability of venules, and increased mucus secretion by goblet cells

Back 43

histamine

Front 44

interaction of histamine with this receptor increases vasopemeability and vasodilation, stimulates endocrine glands, and increases the release of acid in the stomach

binding of histamine to this receptor on mast cells and basophils suppresses degranulation; thus, histamine exerts negative feedback on the release of mediators

Back 44

H2

Front 45

as secondary messengers, are not formed until the mast cell undergoes degranulation and the enzymatic breakdown of phospholipids in the plasma membrane

their effects take longer to become apparent, but are more pronounced and longer lasting than those of histamine

Back 45

leukotrienes and prostaglandins

Front 46

mediate bronchoconstriction, increased vascular permeability, and mucus production

secondary mediator

Back 46

leukotrienes

(prostaglandin D2 also causes brochoconstriction)

Front 47

in humans, the _____ are thought to contribute to the prolonged brochospasm and buildup of mucus seen in asthmatics

Back 47

leukotrienes

Front 48

stimulate a Th2 response and thus increase IgE production in B cells

Back 48

IL-4 and IL-13

Front 49

especially important in the recruitment and activation of eosinophils

Back 49

IL-5

Front 50

high concentrations secreted by mast cells may contribute to shock in systemic anaphylaxis

Back 50

TNF-alpha

Front 51

a shock-like and often fatal state, the onset of which occurs w/in minutes of a type I hypersensitivity reaction, usually initiated by an allergen introduced directly into the bloodstream or absorbed from the gut or skin

Back 51

systemic anaphylaxis

Front 52

afflict at least 20% o the population in developed countries, include a wide range of IgE-mediated disorders, including allergic rhinitis (hay fever), asthma, atopic dermatitis (eczema), and food allergies

Back 52

atopic allergies

Front 53

most common atopic disorder, affecting 10% of the US population

results from the inhalation of common airborne allergens and subsequent reaction with sensitized mast cells in the conjunctivae and nasal mucosa, inducing the release of pharmacologically active mediators from mast cells

symptoms include watery exudation of the conjunctivae, nasal mucosa, and upper respiratory tract as well as sneezing and coughing

Back 53

allergic rhinitis
(hay fever)

Front 54

commonly known as hives

result from when a food allergen is carried to sensitized mast cells in the skin, causing swollen (edematous) red (erythematous) eruptions

Back 54

atopic urticaria

Front 55

an inflammatory disease of skin that is frequently associated w/ a family history of atopy

observed most frequently in young children

unlike a delayed-type hypersensitivity reaction, which involves Th1 cells, the skin lesions in _____ ______ contain Th2 cells and an increased number of eosinophils

Back 55

atopic dermatitis

Front 56

as a type I hypersensitivity reaction begins to subside, mediators released during the course of the reaction often induce localized inflammation called the _____ _____ _____

characterized by infiltration of neutrophils, eosinophils, macrophages, Th2 cells, and basophils

Back 56

late-phase reaction

Front 57

Th1 cell affect on type I hypersensitive reactions

Back 57

reduce response

Front 58

Th2 cell affect on type I hypersensitive reactions

Back 58

enhance response

Front 59

IL-4 and IL-13 contribution to type I response

Back 59

enhance class switching to IgE and regulate the clonal expansion of IgE-committed B cells

Front 60

IL-4 and IL-9 contribution to type I response

Back 60

enhance mast-cell production

Front 61

IL-5 and IL-9 contribution to type I response

Back 61

enhance eosinophil maturation, activation, and accumulation

Front 62

cytokine produced by Th1 cells that inhibits the type I response

Back 62

IFN-gamma

Front 63

immunotherapy with repeated injections of increasing doses of allergens

Back 63

hyposensitization

Front 64

an antibody such as IgG that competes for the allergen, binds to it, and forms a complex that can be removed by phagocytosis; as a result, the allegen is not available to cross-link the fixed IgE on the mast-cell membranes, and allergic symptoms decrease

Back 64

blocking antibody

Front 65

involve antibody-mediated destruction of cells

Back 65

type II hypersensitivity
antibody-mediated cytotoxic hypersensitivity

Front 66

antibodies to the A, B, and O antigens
usually of the IgM class

Back 66

isohemaglutinins

Front 67

develops when the maternal IgG antibodies specific for fetal blood-group antigens cross the placenta and destroy fetal RBCs

consequences of such a transfer can be minor, serious, or lethal

Back 67

hemolytic disease of the newborn

Front 68

severe hemolytic disease of the newborn

most commonly develops when an Rh+ fetus expresses an Rh antigen on its blood cells that the Rh- mother does not express

Back 68

erythroblastosis fetalis

Front 69

antibodies against the Rh antigen administered to the mother at around 28 weeks of pregnancy and w/in 24-48 hours after the first delivery

bind to any fetal RBCs that may have entered the mother's circulation and facilitate their clearance before B-cell activation and ensuing memory-cell production can take place

Back 69

Rhogam

Front 70

in this procedure, a cell separation machine is used to separate the mother's blood into two fractions, cells and plasma

the plasma containing anti-Rh antibody is discarded, and the cells are reinfused into the mother in an albumin or fresh-plasma solution

Back 70

plasmapheresis

Front 71

drug-induced hemolytic anemia is a type ___ response

Back 71

type II response

Front 72

certain antibiotics can absorb nonspecifically to proteins on RBC membranes, forming a complex similar to a hapten-carrier complex

in some patients, such drug-protein complexes induce formation of antibodies, which then bind to the absorbed drug on RBCs, inducing complement-mediated lysis and thus progressive anemia

Back 72

drug-induced hemolytic anemia

Front 73

hypersensitivity reactions caused by large amounts of immune complexes

Back 73

type III hypersensitivity
immune complex-mediated hypersensitivity

Front 74

deposition of immune complexes in type II responses results in the recruitment of ________ to the site

the tissue there is injured as a consequence of granular release from the ______

Back 74

neutrophil

Front 75

these complement split products cause localized mast-cell degranulation and consequent increase in local vascular permeability

Back 75

C3a and C5a
anaphylatoxins

Front 76

localized intradermal or subcutaneous injections of antigens may lead to formation of localized immune complexes, which mediate an acute ____ reaction w/in 4 to 8 hours

type III response

Back 76

Arthus reaction

Front 77

accumulation of fluid

Back 77

edema

Front 78

accumulation of RBCs

Back 78

erythema

Front 79

in this generalized type III reaction, w/in days or weeks after exposure to foreign serum antigens, an individual begins to manifest a combination of symptoms that are called...

symptoms include fever, weakness, rashes w/ edema and erythema, lymphadenopathy, arthritis, and sometimes glomerulonephritis

Back 79

serum sickness

Front 80

when some subpopulations of activated Th cells encounter certain types of antigens, they secrete cytokines that induce a localized inflammatory reaction called....

Back 80

delayed-type hypersensitivity (DTH)
type IV hypersensitivity

Front 81

characterized by large influxes of nonspecific inflammatory cells, in particular, macrophages

Back 81

DTH
type IV H

Front 82

dendritic cells found in the epidermis

thought to pick up antigen that enters through the skin and transport it to regional lymph nodes, where T cells are activated by the antigen

DTH response activators

Back 82

langerhans cells

Front 83

in this phase, Th1 cells secrete a variety of cytokines that recruit and activate macrophages and other nonspecific inflammatory cells

Back 83

effector phase of DTH response

Front 84

develops when continuous activation of macrophages induces the macrophages to adhere closely to one another, assuming an epithelioid shape and sometimes using to form multinucleated giant cells

Back 84

granuloma

Front 85

IL-3 and GM-CSF involvement in DTH response

Back 85

induce localized hematopoiesis of the granulocyte-monocyte lineage

Front 86

IFN-gamma and TNF-beta (together w/ macrophage-derived TNF-alpha and IL-1) involvement in DTH responses

Back 86

act on nearby endothelial cells, inducing a number of changes that facilitate extravasion of monocytes and other nonspecific inflammatory cells

Front 87

a type of DTH response that occurs commonly after exposure to formaldehyde, trinitrophenol, nickel, turpentine, and active agents in various cosmetics and hair dyes, poison oak and ivy

mediated by Th1 cells

most of these substances are small molecules that complex w/ skin proteins

Back 87

contact dermatitis