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Smooth functioning of the immune system depends on the following features
- Diversity
- Sepcificity
- Memory
- Clonal expansion
- Specialization
- Contraction
- Nonreactivity to self
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Main effector cells of the adaptive immune response are composed mainly of 3 cell types
- B lymphocytes
- T lymphocytes
- Natural killer cells
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What strategy does the B lymphocyte employ to combat microbes
They secrete antibodies that bind to extra-cellular microbes to enhance ingestion and destruction by phagocytes
These antibodies also prevent extracellular microbes from further infecting host cells
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What strategy does the T lymphocyte employ to combat microbes?
They destroy host cells infected w/ intracellular microbes to eliminate the infection
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What strategy does the natural killer cell employ to combat microbes?
- They transfer granzymes into targeted cells, like viruses, resulting in cell destruction
- through apoptosis rather than lysis
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Things to pay attention to when seeing a peds pt w/ a suspected immunodeficiency
- -thorough history w/ delineation of prior infections
- -complete physical exam
- -review of previous diagnostic studies
- -particular attention to chronologic patterns of infection or apparent flares of disease & correlation w/ symptoms or lab results & can be highly suggestive of defects in specific aspects of the immune response
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Evaluation of T cell function is important b/c
- Determines its role in the cellular immune response
- Delineating its role as a contributing factor to the humoral immune response
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Plasma cells are derived from
B cells
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Plasma cells are the only cells in the body capable of
Producing and secreting immunoglobulin
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B cell functionality may be initially evaluated by
quantitative imunglobulin specifically titers of IgA, IgG, and IgM
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Complement describes a family of circulating proteins that act together to promote
- opsonization
- bacteriolysis
- phagocytosis of microorganisms
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Cryoglobulins are
Immnoglobulins that precipitate as serum is cooled below core body temp.
These precipitates can be seen in a multitude of diseases, incl. the vasculitides, chronic infections or autoimmune disorders
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Principal pathophysiologic event in anaphylaxis is
The activation of mast cells and to a lesser extent, basophils
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Antigen specific IgE is produced in genetically susceptible individuals in response to
exposure to any variety of allergens.
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Specific IgE binds to
high-affinity IgE receptors on the surface of mast cells and is available to bind to allergen.
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Allergen reexposure via antigen presenting cells causes
aggregation of receptor bound IgE and this cross linking sets off a series of intercellular signals that very rapidly lead to mast cell activation.
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What chemicals can cause anaphylaxis
- Radiocontrast media
- Components of insect venom
- Opiate analgesics
- Vancomycin
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What medications can cause anaphylaxis
- Vancomycin
- NSAIDs – inhibition of the cyclo-oxygenase enzyme, shifting eicosonoid metabolism toward production of leukotrienes
- Angiontensin converting enzyme inhibitors – increase the concentrations of bradykinin through effects on the kinin-kallikrien forming system
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What physical factors can also cause mast cell activation & anaphylaxis
exercise & exposure to cold - through as-yet unidentified mechanisms
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where are preformed mediators stored
intracellular granules
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which preformed mediator is the most important?
histamine
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Examples of other preformed mediators are
- Protease – tryptase, carboxypeptidase, chymase
- Proteoglycans – heparin & chondroitin sulfate
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Which organs do the preformed and newly formed mediators affect most importantly
- The vasculature
- The heart
- The lungs
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How is the vasculature affected by mediators?
- Vasodilation
- Increased permeability
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What does the impact of the mediators on the vasculature result in?
Distributive and hypovolemic hypotension Shock
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How is the heart affected by mediators – esp histamine?
- Vasospasm of coronary arteries
- Shortening diastole – by effecting the sinoatrial node
- Decreasing coronary blood flow
- Delays in atrioventricular conduction
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What does the impact of the mediators on the heart result in?
Cardiogenic shock
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How are the lungs affected by mediators?
- Laryngeal edema – d/t increased vascular permeability in the larynx
- Bronchospasm – stimulated bronchial smooth mm contraction
- Increased viscosity of the mucous
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What does the impact of the mediators on the lungs result in?
Significant bronchoiolar mucus plugging
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Nonlife threatening manifestations of anaphylaxis include
- Flushing
- Pruritis
- Urticarial/angioedema
- Rhinorrhea
- Sneezing
- Conjunctivitis
- Headache
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Primary immunodeficiency diseases (PID) affect
- neutrophils
- macrophages
- dendritic cells
- complement proteins
- natural killer cells
- t lymphocytes
- b lymphocytes
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factors to consider when beginning to evaluate a peds patient who may have primary immunodeficiency disease
- birth hx w/ maternal risk factors, length of gestation, birth weight, neonatal problems - delayed separation of the umbilical cord, jaundice, respiratory problems
- growth & development over time - any problems w/ FTT, any motor (fine or gross) development, language, cognitive
- immunization hx
- medication (past & present)
- family history
- infection history
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HIV infection occurs when the
virus enters the body and binds to CD4 receptors on host T lymphocytes
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Juvenile Idiopathic Arthritis (JIA)
autoimmune disease w/ genetic and environmental components
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Arthritis is definied clinically
as the presence of joint swelling accompanied by warmth or tenderness or limitation of motion with tenderness on motion
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Systemic Lupus Erythematosus (SLE) is
a multisystem inflammatory autoimmune disease
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SLE is characterized by
the presence autoantibodies, especially antinuclear antibodies
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Vasculitis can be
the result of conditions or diseases such as autoimmune disorders and drug reactions
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vasculitic disorders are characterized by
necrosis and inflammation of the blood essels
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