40 Questions
What happens to a majority of effector lymphocytes after a microbe is eliminated?
What is the role of antibodies secreted by plasma cells?
They promote the phagocytosis and destruction of pathogens
What is the result of immune responses that are normally protective?
Tissue injury
What happens to secreting plasma cells after they migrate to the bone marrow?
They live for years, continuing to produce low levels of antibodies
What is the term for diseases resulting from immune responses that normally are protective?
Hypersensitivity diseases
What is the purpose of the initial activation of lymphocytes?
To generate long-lived memory cells
What is the state of the immune system after the elimination of microbes?
Homeostasis
What is conferred to neonates by antibodies?
Passive immunity
Which of the following is TRUE about prostaglandin D2 (PGD2)?
It is the most abundant mediator generated by the cyclooxygenase pathway in mast cells.
What is the main function of acidic proteoglycans in mast cell granules?
To act as a storage matrix for the amines.
What is the primary action of IL-13 in the context of a TH2-initiated immune reaction?
It stimulates epithelial cell mucus secretion.
What is the role of mast cells in immediate hypersensitivity reactions?
They release compounds that mediate type I hypersensitivity reactions.
What is the primary function of ECF in the context of immediate hypersensitivity reactions?
To act as an eosinophil chemotactic factor.
What is the role of NCF in the context of immediate hypersensitivity reactions?
To act as a neutrophil chemotactic factor.
What is the primary action of PAF in the context of immediate hypersensitivity reactions?
To act as a platelet-activating factor.
What is the primary function of cytokines in the context of immediate hypersensitivity reactions?
To stimulate inflammation seen in late-phase reactions.
What is the primary effect of systemic vasodilation in an allergic reaction?
Decreased blood pressure
Which of the following is NOT a type of cytokine?
Leukotriene B4
What is the main role of eosinophils in the late-phase response?
To produce major basic protein
What is the outcome of localized allergic reactions in the lung?
Bronchoconstriction
What is the primary source of chemokines in the late-phase response?
TNF-activated epithelium
What is the difference between localized and systemic allergic reactions?
Localized reactions are confined to a specific site
What is the role of PAF in allergic reactions?
To activate platelets
What is the time frame for progression to circulatory collapse and death in anaphylactic shock?
Minutes
What type of hypersensitivity is characterized by the release of TH2 cytokines and the production of IgE antibodies?
Type I
Which of the following proteins are toxic to epithelial cells?
Protein and eosinophil cationic protein
What is the term used to describe a familial predisposition to localized type I reactions?
Atopy
Which of the following genes are implicated in susceptibility to asthma and other atopic disorders?
All of the above
What is the main function of inflammatory leukocytes in immediate hypersensitivity?
To amplify and sustain the inflammatory response
What is the primary goal of therapy in treating allergic diseases such as asthma and atopic dermatitis?
To modulate the inflammatory response
What is the role of ADAM33 in atopic disorders?
It is involved in tissue remodeling in the airways
What is the relationship between type I hypersensitivity and human disease?
Type I hypersensitivity is an important defense mechanism against parasites, but can also contribute to human disease
What is the name of the pathological lesion that occurs in blood vessels?
Vasculitis
What is the result of antibody-coated cells being phagocytosed by macrophages?
Depletion of the opsonized cells
What type of antibodies are capable of inducing lesions?
IgG and IgM
What is the result of the interactions between immune complexes and leukocytes?
Secretion of prostaglandins, vasodilator peptides, and chemotactic substances
What is the term used to describe the lesion that occurs in renal glomeruli?
Glomerulonephritis
What is the result of the activation of Hageman factor?
Augmentation of the inflammatory process
What is the term used to describe the lesion that occurs in joints?
Arthritis
What is the result of immune complexes depositing in tissues or blood vessels?
Acute inflammatory reaction
Study Notes
Immune Response and Hypersensitivity Reactions
- Plasma cells secrete antibodies that neutralize microbes, block their infectivity, and promote phagocytosis and destruction of pathogens.
- Antibodies also confer passive immunity to neonates, and Immunologic Memory is generated.
Decline of Immune Responses
- After an infectious pathogen is eliminated, most effector lymphocytes die by apoptosis, returning the immune system to its basal resting state.
- This return to homeostasis occurs because microbes provide essential stimuli for lymphocyte survival and activation.
- Activated lymphocytes are no longer kept alive as the stimuli are eliminated.
Hypersensitivity Reactions
- Immune responses can cause tissue injury, resulting in hypersensitivity diseases.
- Hypersensitivity reactions are grouped into several categories, including immediate hypersensitivity reactions.
- Immediate hypersensitivity reactions involve IgE antibodies and are responsible for allergic reactions.
Immediate Hypersensitivity Reactions
- Mast cells synthesize and secrete prostaglandins and leukotrienes, which have several actions important in immediate hypersensitivity reactions.
- These lipid mediators can cause intense bronchospasm, increased mucus secretion, and promote inflammation.
- Eosinophils produce toxic proteins and cytokines that promote inflammation and epithelial cell injury.
Localized Allergic Reactions
- Local reactions occur when the antigen is confined to a particular site, such as skin (contact, causing urticaria), gastrointestinal tract (ingestion, causing diarrhea), or lung (inhalation, causing bronchoconstriction).
- Examples of localized allergic reactions include hay fever, asthma, and certain forms of asthma.
Susceptibility to Hypersensitivity Reactions
- Susceptibility to localized type I reactions has a strong genetic component, and the term atopy is used to imply familial predisposition to such localized reactions.
- Genes implicated in susceptibility to asthma and other atopic disorders include those encoding HLA molecules, cytokines, and ADAM33, a metalloproteinase involved in tissue remodeling in the airways.
Inflammation and Tissue Injury
- Inflammation is a major component of many allergic diseases, notably asthma and atopic dermatitis.
- Therapy usually includes anti-inflammatory drugs such as corticosteroids.
- Leukocytes recruited to the site of inflammation can amplify and sustain the inflammatory response even in the absence of continuous allergen exposure.
- Inflammatory leukocytes are responsible for much of the epithelial cell injury in immediate hypersensitivity reactions.
This quiz covers the processes involved in immune responses, including the role of plasma cells, antibody production, and immunologic memory.
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