Hypersensitivity And The Lung Flashcards
What does the immune system (cellular response) comprise of?
Phagocytes e.g. monocytes and neutrophils phagocytose (envelop the invader) and some present to other cells
Lymphocytes: make and release antibodies and kill diseased cells
What does the immune system (humoral response) comprise of?
Immunoglobulins
Complement (form membrane attack complex)
Cytokines (allow communication between leukocytes and tissue cells)
What are antibodies?
Produced by B-lymphocytes (plasma cells)
Neutralises or eliminates pathogens
May also cause disease…
What does IgM do?
IgM: Circulating tetramers made at the beginning of infection.
What does IgG do?
IgG: Monomer highly specific antibodies targeting single epitopes.
What does IgE do?
IgE: Likely to have developed in response to parasitic threats. Implicated in allergy, particularly alongside eosinophils
What does IgA do?
IgA: Expressed in mucosal tissue. Forms dimers. Protects the neonatal gut (expressed in breast milk)
What does IgD do?
IgD: Monomers, induction of antibodies in B cells, activates basophils and mast cells
What is the Gell and Coombs Classification?
Recognition of foreign antigen can cause collateral tissue damage
Conceptualised in the early 1960s
Imperfect classification, but still holds as description of pathology
Does not hold well for complex immune reactions
What happens in Type 1 hypersensitivity?
Antigen interacts with IgE bound to mast cells or basophils
Degranulation of mediators lead to local effects
Histamine the predominant mediator
What happens when someone has an anaphylaxis shock due to peanuts?
Sudden onset
Systemic degranulation of mast cells and histamine release
Skin, eyes, lips swelling, hypotension
Bronchospasm can result in airway occlusion and death if not quickly and accurately managed.
What is the management to anaphylaxis shock due to peanuts?
Adrenaline 0.5mg (1:1000) or auto injector in community intramuscularly
Steroids
Antihistamines
Observation (second peak may occur circa 12 hours)
Tryptase measurements
What happens in Type 2 hypersensitivity?
Antibodies reacting with antigenic determinants on the host cell membrane
Usually IgG or IgM
Outcome depends on whether complement is activated and if metabolism of cell is affected
What is Anti Glomerular Basement Membrane Disease?
Rare but deadly type II HS disease
Goodpasture syndrome = alveolar involvement
GBM is made of type IV collagen present in alveoli and kidneys (glomeruli)
Alpha 3 subunit becomes antigenic
What is the diagnosis for Anti Glomerular Basement Membrane Disease?
Diagnosis requires high degree of clinical suspicion
GBM antibodies in serum or on biopsy (usually of kidney)
