IMMUNOLOGY QUIZ 2 Flashcards
(98 cards)
TYPE I HYPERSENSITIVITY CELLS and ANTIBODIES
mast cells and basophils with preformed histamine and high affinity receptors for IgE.
IgE
CD40 LIGAND/CD154
made by CD4+ Th2 cells to stimulate B cells isotype switching. Binds to CD40 on B cell surface.
TYPE II HYPERSENSITIVITY CELLS AND ANTIBODIES
CELLS: macrophages, NK cells, neutrophils, eosinophils
Antibodies: IgG, IgM, complement
TYPE III HYPERSENSITIVITY CELLS AND ANTIBODIES
Ag-Ab complexes (mostly IgM and IgG), complement
TYPE IV HYPERSENSITIVITY CELLS AND ANTIBODIES
CELLS: sensitized T cells, NK cells, macrophages
no antibodies
TYPE I HYPERSENSITIVITY TIME COURSE AND CLINICAL CONSEQUENCES
Timing: Occur after prior sensitization. Occurs within minutes.
Consequences:
skin: edema, wheal, flare, hives
pulmonary: bronchospasm, edema
CV: hypotension, arrhythmias, CV collapse
GI: cramps, vomiting, diarrhea
How does histamine mediate IMMEDIATE hypersensitivity?
Histamine: act on H1 receptors (contract SM, increase mucous, increase vascular permeability), act on H2 receptors (increase gastric secretion, decrease mediator released by basophils and mast cells).
How does PROSTAGLANDIN mediate IMMEDIATE hypersensitivity?
vasodilation, edema, bronchoconstriction.
How do SRS-A and Leukotrienes C4, D4, E4 mediate IMMEDIATE hypersensitivity?
constrict airways, increased permeability of vessels, vasodilation, increase mucous.
How does LEUKOTRIENE B4 mediate IMMEDIATE hypersensitivity?
causes neutrophil chemotaxis, adhesion of neutrophils to endothelium, neutrophil degranulation.
How do PAF mediate IMMEDIATE hypersensitivity?
produced by mast cells. Aggregate platelet, vasodilation, bronchoconstrictor, chemotaxis and degranulation in eosinophils and neutrophils.
How do PROTEASES mediate IMMEDIATE hypersensitivity?
activate kinins, complement, vascular permeability?
What are the mediators of PRO-INFLAMMATORY reactions by chemotaxis and mast cell activation?
- Leukotriene B4
- IL-8, C5a, PAF
- Anaphylatoxins (C3a, C4a, C5a)
What are the TREATMENTS for Type I hypersensitivity?
- Histamine receptor antagonists (benadryl)
- Leukotriene receptor antagonists
- IgE antibodies
- Synthetic glucocorticoids
- Epinephrine and long acting beta-2 receptor agonists
What is SCIT?
Treatment of TYPE I hypersensitivity. Involves hyposensitization subcutaneously. Activate T-reg cells to increase allergen-specific IgG and IgA that decrease allergic reactions (divert attention away from IgE).
What are genetic and environmental factors that influence allergies?
- HLA - associate with particular antigens
2. Environment: living on farms (decrease risks of asthma), exposed to things are good.
Mast cell
Have granules preloaded with Histamines and other enzymes.
Have high affinity FcERI (receptors for IgE Fc region).
IgE + Ag activate mast cells to degranulate WITHIN SECONDS.
Basophils
Also release mediators with mast cells.
Also have FcERI.
Have H2 receptors that provide NEGATIVE FEEDBACK to subdue mediator release.
Sensitization
After first exposure to allergen –> activates Th2 cells –> stimulate class switching of IgE in B cells –> produce IgE –> binding of IgE to FcERI on mast cells.
IgE
VERY short half-life.
very high affinity for mast cells
TISSUE half-life is LONG.
Fc-gamma Receptor
Receptors for IgG Fc region. Has LOW AFFINITY and INHIBITS B cell, mast cell, and DC activation.
Hyposensitization
Downregulate Th2.
Upregulate Th1.
Involves SCIT by incrase doses of antigen to activate T-REGS and increase IgG and IgA.
Atopy
Presence of specific IgE antibodies against common environmental allergens.
ADCC
Antibody dependent cellular cytotoxicity. Antibody coats cell –> trigger Fc-gamma RIII binding by NK, PMN cells –> release toxic molecules –> lysis of antibody-coated cell.