Allergies Flashcards
What are autoimmune disorders?
Where the immune system attacks our own bodies.
What causes allergies?
Overproduction of IgE antibodies in response to harmless environmental antigens.
Give some examples of allergies.
- Asthma
- Hay fever
- Allergic rhinitis
- Hives
- Dermatitis
- Food allergy
- Drug allergy
What is an allergy?
Exaggerated immune response to a foreign antigen.
What is atopy?
State that leads to an exaggerated IgE-mediated immune response.
Atopic disorders are what type of disorders?
Type 1 hypersensitivity disorders.
An allergy involves cytokines produced by which type of cells?
- Th2 cells
- IgE
- Mast cells
- Eosinophils
State some symptoms of asthma.
- Wheeze
- Breathlessness
- Chest tightness
- Cough
What are the common allergens of asthma?
- Inhales allergens
- Food
- Drugs
State some symptoms of rhinitis.
- Nasal itching
- Blockage
- Rhinorrea
- Sneezing
What is urticaria and angiodema?
Itchy, nettle rash - hives.
What are urticaria and angiodema triggered by?
- Food
- Drugs (NSAIDs and ACEi)
What is eczema?
Erythematous inflammation of the skin.
What is anaphylaxis?
Severe allergic reaction.
For Type 1 hypersensitivity allergens, list some drugs.
- Penicillin
- Sulfonamides
- Local anesthetics
- Salicylates
Explain what happens during the first and second exposure to pollen.
1st exposure: IL-4 causes B cells to produce IgE in response to antigens. IgE binds to mast cells.
2nd exposure: Acute release of mast cells contents causes allergic rhinitis (hay fever)
Explain the process of the activation of an allergic response.
- Allergens enter mucosa and is detected by dendritic cells.
- Dendritic cells take allergens to lymph nodes. Activation of T and B cells. B cells converted into plasma cell.
- Plasma cells travel back to mucosa and produce IgE antibodies.
- IgE binds to mast cells which triggers mast cells degranulation.
Explain the mechanism of type 1 hypersensitivity.
IgE-mediated mast cell and basophil degranulation -> release of vasoactive mediaters.
What is the main functions of mast cells?
- First-line of defence
- Release granule contents.
- Inflammation
What is the role of mast cells during inflammation?
- Pathogens enter at site of wound which attract mast cells and macrophages. Mast cells release Histamines. Macrophages engulf pathogens and release inflammatory cytokines.
- Neutrophils and monocytes attracted to wound. Neutrophils undergo phagocytosis. Monocytes promote tissue healing.
- Pathogen removed.
Which two type of cells initiate and inflammatory response?
- Mast cells
- Basophils
Where are mast cells found?
Connective tissue surrounding blood vessels and mucosal surfaces.
Where are basophils found?
Blood circulation.
What effect does mast cell activation and granule release have on the GI tract?
- Increased fluid secretion
- Increased peristalsis
What effect does mast cell activation and granule release have on the eyes, nasal passages and airways?
- Decreased diameter
- Increased mucus secretion
What effect does mast cell activation and granule release have on blood vessels?
- Increased blood flow
- Increased permeability
What are the granule contents of Mast cells?
- Histamines
- Leukotrienes
- Inflammatory cytokines
- Neutrophil and eosinophil chemokines
What are the granule contents of eosinophil?
- Matrix metalloproteinases and collagenases
- Fibrotic cytokines
- T and B cell attracting chemokines
What is the effects of histamine in type 1 hypersensitivity reactions?
- Capillary and venous dilation
- Increased vascular permeability
- Contraction of smooth muscle.
What are the 2 phases of an allergy?
Immediate phase and late phase
What are the main processes that occur during the immediate phase of an allergy?
- Mast cell degranulation
- Histamine release
What are the main processes that occur during the late phase of an allergy?
- Immune response
- Eosinophil migration
What is the effects of the granules which are part of eosinophils?
- Contain enzymes that are harmful to the cell walls of parasites.
- Can damage host tissues
What happens during the early phase of an allergic response?
- Mucus production
- Vasodilation and swelling
- Bronchoconstriction
What happens during the late phase of an allergic reaction?
- Recruit immune cells into peripheral tissues
- Smooth muscle scarring
What is the effect of histamine in the body when pathogens enter subcutaneously?
Inflammation of connective tissue and capillaries.
What is the effect of histamines in the body when pathogens enter by ingestion?
- Inflammation of the epithelium and capillaries.
- Contraction of intestinal smooth muscle.
What is the effect of histamines in the body when pathogens enter intravenously?
Inflammation of the capillaries and connective tissue.
What is the effect of histamines in the body when pathogens enter via inhalation?
- Inflammation of epithelium and capillary. - - Contraction of the brochial smooth muscle.
- Mucus production
