PLN - Allergy stuff

allergies

• inappropriate or excessive immune responses to antigens

• excessive response by IgE antibodies

IgE

• attaches as an individual molecule to the exposed surfaces of basophils and mast cells

• when an antigen bound by IgE molecules

  • cell releases histamine and other chemicals to accelerate inflammation in the immediate area

  • attempt to trap the molecule which was present

• Allergic response

allergens

• antigens that trigger allergic reactions

4 categories of allergic reactions

• imediate hypersensitivity type 1

• cytotoxic reactions type 2

• immune complex disorders type 3

• delayed hypersensitivity type 4

Type 1 allergy - Immediate hypersensitivity

• rapid and severe response to the presence of an antigen

• most commonly recognized type of allergy

• includes allergic rhinitis (environmental allergies)

• Sensitization leads to

  • production of large quantities of IgE antibodies distributed throughout the body

• Secondary exposure

  • the over produced IgE leads to

• severity leads to

  • individual sensitivity and what locations are involved

• Allergens in blood stream can lead to anaphylaxis

Anaphylaxis

• can be fatal

• affects cells throughout the body

• changes capillary permeability

  • produces swelling or hives on the skin

• Smooth muscles of the respiratory system contract

  • make breathing difficult

• Peripheral vasodilation can lead to circulatory collapse

  • anaphylactic shock

Mechanism for anaphylaxis

• Primary response

  • allergen fragment attaches to a fixed macrophage

    • activates Th cell → helps activate the B cell

  • B cell is sensitized and activated

  • Plasma cell

  • produces IgE antibodies

• Secondary exposure

  • sensitized mast cell and basophils

  • binds antigen and gets stimulated

  • release histamines, leukotrienes and other chemicals that cause pain and inflammation

    • capillary dialation, permiability, airway constriction, mucus secretion, pain and itching