Hypersensitivities 1-4 Part 1

Question 1

What is physiology of a type 1 hypersensitivity?

Answer 1

Antigen exposure causes release of vasoactive substances such as histamine, prostaglandins, and leukotrienes from mast cells or basophils. This response is usually but not always IgE-dependent

Question 2

What are examples of type 1 hypersensitivity

Answer 2

anaphylaxis, angiodema, bronchospasm, urticaria, allergic rhinitis (AR)

Question 3

What is the physiology of type 2 hypersensitivity?

Answer 3

An antigen or hapten that is intimately associated with a cell binds to antibody, leading to cell or tissue injury

Question 4

What are examples of type 2 hypersensitivies?

Answer 4

hemolytic anemia, interstitial nephritis

Question 5

Explain how hypersensitivities are on a spectrum and how this affects a treatment plan?

Answer 5

Understand that hypersensitivity diseases, especially allergic reactions, manifest on a wide spectrum
A person may have minimal symptoms, or a person may have life-threatening symptoms!
Your approach to managing the patient will depend on where they lie on the spectrum

Question 6

Describe in detail the process of type 1 IgE mediated disorders.

Answer 6

Immediate reactions that are triggered by binding of an allergen to a specific IgE that is found on the surface of a mast cell or basophil
Mast cells and basophils have granules that contain potent mediators of allergic reactions
During the sensitization or priming stage, the allergen-specific IgE antibodies attach to receptors on the surface of these mast cells and basophils
With subsequent exposure, the sensitizing allergen binds to the cell-associated IgE and triggers a series of events that ultimately leads to degranulation of the sensitized mast cell or basophil

Question 7

What are the mediators of allergic reactions?

Answer 7

Histamine
Complement
Acetylcholine-bronchiole smooth muscle contraction
Leukotrienes and Prostaglandins-more prolonged histamine like effects
Kinins
Eosinophils-recruit more eosinophils

Question 8

What are the 2 main subgroups IgE mediated allergy?

Answer 8

1. Atopy-state of being hyperallergenic (AR, asthma, allergic gastroenteropathy),
2. Anaphylaxis

Question 9

What is urticaria?

Answer 9

hives-circumscribed wheals on a erythematous base on the skin, can be few mm-several cm, serpiginous borders, can last 12-24 hrs but generally shorter duration.

Question 10

What angioedema?

Answer 10

related to urticaria but involving the deeper layers of the skin and generally manifests with facial, throat and tongue swelling.

Question 11

What are some specific presentations of urticaria and angiodema?

Answer 11

dermatographisms (skin drawing), pressure urticaria, cold urticaria, cholinergic urticaria, aquagenic urticaria, solar urticaria

Question 12

What is the main goal of the history questions regarding hypersensitivity?

Answer 12

To identify the specific cause or precipitant

Question 13

What types of substances should be avoided that can aggravate hypersensitivities?

Answer 13

ASA, NSAIDS, ETOH, ACE inhibitors

Question 14

What are some special considerations with chronic urticaria?

Answer 14

carefull with steroids (S/E can be worse than disease), educate the patient-often times cause is not found, many patients are free of lesions within a year, investigate thyroid and for H. Pylori, prescribe epipens with anyone with sever angioedema or anaphylaxis

Question 15

Describe anaphylaxis

Answer 15

allergic, IgE-mediated and immediate hypersensitivity reaction to a protein substance. sx’s develop in 5-60 mins

Question 16

Describe anaphylactoid?

Answer 16

clinically presents the same as anaphylaxis but is caused by mast cell destruction and release of granule component

Question 17

How will a patient with anaphylaxis present?

Answer 17

pruritis, flushing, impending doom, urticaria, angioedema, in 50% (sob, wheezing, laryngeal edema, can lead to respiratory failure), 30% shock from increased vascular permeability.

Question 18

How do you manage someone with anaphylaxis?

Answer 18

It depends on severity but may include: intubation, large bore IV fluids, O2, epinephrine, antihistamines, bronchodilators, corticosteroids

Question 19

What are common medication allergies?

Answer 19

beta-lactam antibiotics(penicillins, cephalosporins), sulfonamides (trimethoprim/sulfamethoxazole (Bactrim, Septra), phenytoin, carbazepine (Tegretol), allopurinol, NSAIDS

Question 20

What are common drug allergy reactions?

Answer 20

urticaria, angioedema, anaphylaxis, exanthems (rash), vasculitis, exfoliative dermatitis/erythroderma, Steven Johnson’s syndrome, erythema multiform, photosensitivity.

Question 21

Whats important to remember in patients who claim to be allergic to penicillin?

Answer 21

Many of patients claiming to be allergic are actually able to tollerate treatment. Many are falsely labelled allergic.

Question 22

What is the most important fundamental question to ask someone presenting with allergic reaction?

Answer 22

are there systemic reactions or sob?