Immunology Flashcards
(45 cards)
What barrier defences do we have?
Physical: skin, lungs and gut
Active: cillia in lungs, secretions,
What are the key features of innate immunity?
- Ready to activate at any time
- No memory
- Low specificity
- Generic response
- Recognises pathways as a whole
- Essential to life
What happens when the innate system is activated ?
- Recognise the problem (Pattern Recognition Receptors)
- Reaction - e.g. cytokines which attract cells of the innate system to the site of infection
- Deal with the problem - phagocytosis, inflammation, and recruitment of the adaptive immune response.
What are the cells of the innate immune system?
- Cells that recognise the threat - Antigen Presenting Cells (Dendritic and macrophages)
- Contain and destroy threat - phagocytes and granulocytes
What are the proteins of the innate system?
Acute phase proteins, cytokines and complement cascade of proteins
What is phagocytosis?
Phagocytes consume microbes and dying cells
Where are immune cells derived from?
From haematopoeisis - bone marrow pre-cursors
What are the 3 mechanisms of complement activation?
- Classical
- Lectin
- Alternative
What are the consequences of complement activation?
- Inflammation (complement components - c3a) trigger the release of histamine which increases vascular permeability
- Cytolysis
- Opsonisation (Complement components c3b bind to microbrial surface and promote phagocytosis
- Chemotaxis - c5a is a neutrophil chemoattractant
- Inactivation of complement - regulatory proteins limit damage to host cells that may be caused by complement
What are the key features of the adaptive immune system?
- Highly specific to the pathogen
- Can rapidly produce high quality immune response
- Memory
What is the function of T cells?
They are conductors of the immune response. They differentiate into different types of cells
What are the different types of T cells and their function?
Cytotoxic - directly kill cells
Th1 and Th2 produce cytokines which help upregulate the immune response
T regulatory cells - help contract system down - by producing anti-inflammatory cytokines
What is the function of MHC?
Binds peptide fragments of the pathogen and display them on cell surface for recognition by the appropriate T cells
What T cell do MHC I molecules present to?
Cytotoxic
What T cell do MHC II molecules present to?
T helper cells
What is immunoglobulin?
Class of glycoproteins which function as antibodies (produced by the B lymphocytes)
What are the 5 classes of Immunoglobulin?
- IgG
- IgA
- IgM
- IgD
- IgE
What are the two types of hypersensitivity? (Allergy)
TYPE I = immediate, quick recovery, life threatening e.g nut allergy
TYPE IV = > 4 hours, often a fay or 2 after antigen exposure. More difficult to resolve, more difficult to find the allergen e.g. contact dermatitis
What happens immunologically in a type I reaction?
- Antigen binds to the specific IgE.
- Antigen cross links IgE and FceRI
- Release of preformed mediators from mast cell
What are the mast cell mediators?
- Histamine
- Prostaglandin
- Leukotrienes
- Tryptase
- PAF (Platelelt Activation Factor)
What do the mast cell mediators cause?
- Vasodilation
- Vascular Permeability
- Heart rate and cardiac contraction
- Glandular secretion
- Bronchoconstriction
- Hypotension
How are parasites killed?
Eosinophils bind to the IgE, and they have oxygen and nitrogen radicals and toxic granules which kill it
What allergy tests are available?
Skin prick testing and patch testing
What are the symptom control treatment for asthma?
- Allergen avoidance
- steroids to relieve inflammation
- B2 agonists to relieve bronchospasm
- Stabilise mast cells
