Final- Hypersensitivities Flashcards
What is the definition of a Hypersensitivity?
response to an Ag that is beyond normal
What are the four types of Hypersensitivity Reactions?
- Type I (immediate/allergies)
- Type II (antibody/cytokines)
- Type III (immune complex)
- Type IV (cell mediated/delayed)
“ACID”
T/F. Only some forms of Hypersensitivity require prior exposure to the antigen.
False– ALL forms require prior exposure
What type of antibodies or cells are involved in each one of the Four hypersensitivites?
- Type I –> IgE
- Type II –> IgM and/or IgG
- Type III –> IgM and/or IgG
- Type IV–> T cells
How much time does it take before clinical signs show up for the each one of the 4 types of hypersensitivities?
- Type I –> less than 30 mins
- Type II –> 5-12 hrs
- Type III –> 3-8 hrs
- Type IV –> 24-48 hours
What type of Hypersensitivity is rapid and always involves IgE and the degranulation of basophils or mast cells?
Type I (anaphylactic/ allergies)
What type of Hypersensitivity involes IgM or IgG antibodies binding ot cell membranes or ECM and the Ag may be you or exogenous molecules?
Type II (cytokine)
What type of Hypersensitivity involves IgM or IgG antibodies binding to soluble Ag’s and forming an anitbody complex and inflammation takes place at sites of deposition of the complexes?
Type III (immune complexes)
What type of Hypersensitivity involves direct attack of WBCs w/o using antibodies and T cells initiate the inflammation?
Type IV (delayed type)
What type of hypersensitivity is anaphylactic shock from drug injection and insect venom an example of?
Type I
What type of hypersensitivity is arthus reactions or serum sickness an example of?
Type III
What type of hypersensitivity is transfusion reactions and Rh incompatibility an example of?
Type II
What type of hypersensitivity is a rejection of transplanted tissues, contact dermatitis,– like poison ivy, or certain chronic diseases such as Tb examples of?
Type IV
What occurs on the initial exposure for a Type I hypersensitivity?
- allergen enters body
- APC eats it
- APC presents peptides from allergen on MHC II’s
- Helper T cells are activated –> differentiate into the Th-2 subtype (GI system and parasites)
- Th-2 cells activate B cells that are specific for allergen
- B cells (plasma cells) make IgE specific to allergen (Ag)
When an individual is first exposed to an allergen, do they have a reaction?
may not have initial allergic reaction; it takes time for IgE antibodies to accumulate and load onto mast cells
For a Type I Hypersensitivity describe what is occurring during Sensitization. What will a second exposure cause?
- IgE antibodies’ Fc regions bind w/ high affinity to mast cells (which are everywhere in body)
- Second exposure will ACTIVATE mast cells and degranulation will occur
What occurs during Re-Exposure for a Type I Hypersensitivity?
allergen will bind to IgE antibodies which are attached to Mast Cells via there Fc region —-> this will cause degranulation of mast cells and release of chemistry
What does the chemistry released by mast cells during the allergic reaction of a Type I hypersensitivity include?
- vasocative amines (histamine)
- prostaglandins
- leukotrienes
- recruitment of other WBCs (neutrophils and eosinophils)
- leaky vessles, edema, smooth muscle spasms, increased mucus secretion, drop in BP
What “type” of a Type I hypersensitivity involves being injected via insect sting and may result in shock which could be deadly?
Systemic Anaphylaxis
What “type” of a Type I hypersensitivity involves generally ingested or inhaled, but could be systemic?
Localized Anaphylaxis
What are examples of upper respiratory Type I Reactions? How are they Tx?
(hay fever)
- itchy eyes, congestion, sneezing
- pollen, pet dander, dust mite feces
Tx: antihistamine
What is an example of a lower respiratory Type I reactions? How is it Tx?
- asthma
Tx: epinephrine, albuterol
What are some common causes and symptoms of a Gastrointestinal Type I reaction?
NOT food intolerance!!!!
Causes: Eggs, peanuts, tree grown nuts, milk, soy, fish, wheat, peas
Symptoms: hives
How can one prevent a Type I reaction? What is short term Tx for it? What is long term Tx?
avoid contact and get a skin test to Dx
Short term–> antihistamine and epinephrine
Long term–> desensitize and convert IgE and IgG
