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Smooth functioning of the immune system depends on the following features
- Clonal expansion
- Nonreactivity to self
Main effector cells of the adaptive immune response are composed mainly of 3 cell types
- B lymphocytes
- T lymphocytes
- Natural killer cells
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
What strategy does the T lymphocyte employ to combat microbes?
They destroy host cells infected w/ intracellular microbes to eliminate the infection
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
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
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
Plasma cells are derived from
Plasma cells are the only cells in the body capable of
Producing and secreting immunoglobulin
B cell functionality may be initially evaluated by
quantitative imunglobulin specifically titers of IgA, IgG, and IgM
Complement describes a family of circulating proteins that act together to promote
- phagocytosis of microorganisms
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
Principal pathophysiologic event in anaphylaxis is
The activation of mast cells and to a lesser extent, basophils
Antigen specific IgE is produced in genetically susceptible individuals in response to
exposure to any variety of allergens.
Specific IgE binds to
high-affinity IgE receptors on the surface of mast cells and is available to bind to allergen.
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.
What chemicals can cause anaphylaxis
- Radiocontrast media
- Components of insect venom
- Opiate analgesics
What medications can cause anaphylaxis
- 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
What physical factors can also cause mast cell activation & anaphylaxis
exercise & exposure to cold - through as-yet unidentified mechanisms
where are preformed mediators stored
which preformed mediator is the most important?
Examples of other preformed mediators are
- Protease – tryptase, carboxypeptidase, chymase
- Proteoglycans – heparin & chondroitin sulfate
Which organs do the preformed and newly formed mediators affect most importantly
- The vasculature
- The heart
- The lungs
How is the vasculature affected by mediators?
- Increased permeability
What does the impact of the mediators on the vasculature result in?
Distributive and hypovolemic hypotension Shock
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
What does the impact of the mediators on the heart result in?
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
What does the impact of the mediators on the lungs result in?
Significant bronchoiolar mucus plugging
Nonlife threatening manifestations of anaphylaxis include
Primary immunodeficiency diseases (PID) affect
- dendritic cells
- complement proteins
- natural killer cells
- t lymphocytes
- b lymphocytes
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
HIV infection occurs when the
virus enters the body and binds to CD4 receptors on host T lymphocytes
Juvenile Idiopathic Arthritis (JIA)
autoimmune disease w/ genetic and environmental components
Arthritis is definied clinically
as the presence of joint swelling accompanied by warmth or tenderness or limitation of motion with tenderness on motion
Systemic Lupus Erythematosus (SLE) is
a multisystem inflammatory autoimmune disease
SLE is characterized by
the presence autoantibodies, especially antinuclear antibodies
Vasculitis can be
the result of conditions or diseases such as autoimmune disorders and drug reactions
vasculitic disorders are characterized by
necrosis and inflammation of the blood essels