Exam 4 Flashcards
What steps are involved in diagnosis of allergy?
- comprehensive history
- physical exam
- non-immunologic tests
- immunologic tests
What is the purpose of a physical exam when diagnosing allergy?
rule out other causes
examples of immunologic diagnostic tests for allergy
- in-vivo: allergy skin test
- in-vitro: IgE antibody
- provocative and elimination tests
types of skin tests
- cutaneous: prick, puncture, scratch
- intradermal
- in-vivo
skin test: cutaneous
- put a drop of allergen on pt’s skin
- scratch with needle
sensitivity of skin test
- depth of puncture
- amount of langerhans present
- presence of B and T cells in epidermis
risks of intradermal skin test
may hit a capillary with an allergen that pt is allergic to
What are positive results of skin tests?
- wheal
- flare
- happens within 15-30 minutes
How common is testing for immune complex disease done?
Not common; reactions don’t happen until after 2-4 hours and are similar to late phase reactions that occur following positive IgE-mediated reaction
Limitations to skin tests
- not good for food and drugs
- pt should not be on antihistamines or topical corticosteroids when taking skin test
skin test: in-vivo
- reaction may occur up to 48-72 hours
- for delayed hypersensitivity (associated with T cells)
What is an examples of skin tests done in-vivo?
- tuberculin: positive read out: erythema
- patch test: contact dermatitis
examples of in-vitro allergy tests
- IgE testing in blood
- eosinophil count
- blood differential
- serum ig electrophoresis
examples of tests of IgE testing in blood
- RAST (Radioallergosorbent)
- MAST (Multiple allergosorbent)
- FAST (Fluorescent Allergosorbent)
principle of IgE testing in blood
- allergen stuck to a solid phase
- pt’s IgE from serum is exposed to allergen
- anti-human IgE sticks on pt’s IgE
- imaging substrate attached to anti-human IgE
provocative allergen test
challenge with increased dose of allergen
elimination allergen test
get rid of antigen and see if allergic response goes away
Therapies to allergy
- eliminate exposure to allergen
- treat symptoms
- immunotherapy with allergy extracts
other names for immunotherapy
- desensitization
- hyposensitization
mechanism for immunotherapy
administering a small dose of allergen to induce an immune response against the allergen but not large enough of a dose to induce the allergic response itself
route of administration for immunotherapy
- subq
- sublingual
Examples of FDA approved sublingual therapy
- grass pollen: Oralair, Grastek
- ragweed pollen: Ragwitek
- dust mite: Odactra
What are standardized allergenic extracts?
- allergenic extracts that fall within FDA standards
- 19 available
quantity of allergenic extracts
- 900 diagnostic
- 600 therapeutic