Hypersensitivity Flashcards
an excessive or aberrant immune response to any type of stimulus.
Hypersensitivity
The most severe hypersensitive reaction is
Anaphylaxis
An unanticipated severe allergic reaction that is rapid in onset. Characterized by edema in many tissues.
Anaphylactic (Type 1) Hypersensitivity
occurs when antibodies are directed against antigens on cells or basement membranes of tissues.
Cytotoxic (Type II) Hypersensitivity
This reaction can lead to cell lysis and tissue damage.
Cytotoxic (Type II) Hypersensitivity
What is the best example for Cytotoxic (Type II) Hypersensitivity?
Hemolytic Transfusion reaction.
is a damaging inflammatory reaction caused by the insoluble immune complexes formed by antigens that bind to antibodies.
Immune Complex (Type III) Hypersensitivity
is a T cell-mediated immune reaction after exposure to an antigen. This immune reaction typically occurs 24 to 48 hours after exposure to an antigen.
Delayed (Type IV) Hypersensitivity
the antibody typically responsible for allergic reaction belongs to the
IgE isotype
When there is doubt about the validity of the skin tests,
serum-specific IgE test or a provocative challenge test may be performed.
The methods of skin testing include
*prick skin tests
*scratch tests
*intradermal skin testing
it is the most suitable area of the body for skin testing
The back area
is an automated test performed on blood samples by a pathology laboratory.
Serum-specific IgE Test
The serum-specific Ige Test is formerly known as
RAST
What is RAST?
Radioallergosorbent Test (RAST)
Immunoglobulins are grouped into five classes
*IgG
*IgA
*IgM
*IgD
*IgE
IgE-producing cells are located in the
respiratory and intestinal mucosa
refers to IgE-mediated diseases, such as allergic rhinitis
Atopy
are programmed to produce one specific antibody.
B Cells
what are the Primary Chemical Mediators in allergic responses?
*Histamine
*Eosinophil Chemotactic Factor of Anaphylaxis
*Platelet-Activating Factor
*Prostaglandins
What are the Secondary chemical mediators in allergic responses?
*Leukotrienes
*bradykinins
*serotonin
is released by mast cells. It is the first chemical mediator to be released in immune and inflammatory responses.
Histamine
affects the movement of eosinophils to the site of allergens. It is performed in the mast cells and is released from disrupted mast cells.
Eosinophil Chemotactic Factor of Anaphylaxis
is responsible for initiating platelet aggregation and leukocyte infiltration at sites of immediate hypersensitivity reaction.
Platelet-Activating Factor
produce smooth muscle contraction as well as vasodilation and increased capillary permeability.
Prostaglandins
they sensitize pain receptors and increase the pain associated with inflammation.
Prostaglandins
Interpretation of reactions, wheal soft with minimal erythema.
Negative Reactions
Interpretation of reactions, wheal present (5 to 8mm) with associated erythema.
1+
Interpretation of reactions, wheal (7 to 10mm) with associated erythema.
2+
Interpretation of reactions, wheal (9 to 10mm), slight pseudopodia possible with associated erythema
3+
wheal (12 mm+) with pseudopodia and diffuse erythema.
4+
Corticosteroids and antihistamines, suppress skin test reactivity and should be stopped how many hours before testing?
48 to 96 hours
