Partridge (Immune System) Flashcards
What is immunology?
- study of immune system
What is immune system?
- integrated system of cells and molecules that defend against disease, by reacting against infections
What is the medical importance of immunology?
- vaccination
Examples of malfunctions in immune system?
- immunodeficiency
- allergy
- autoimmune disease
- graft rejection
What are immunological techniques?
- research, diagnostics, therapeutics
How do bacteria carry out immune surveillance?
- restriction enzymes
How do invertebrates carry out immune surveillance?
- negative surveillance, cells marked w/ “self” protein labs, unlabelled non-self cells destroyed by phagocytes
How do vertebrates carry out immune surveillance?
- external barriers (skin)
- negative surveillance by major histocompatibility complexes, v polymorphic
- positive surveillance specific recognition of foreign cells (active immunity)
What is the difference between innate and adaptive immune system?
- innate has broad specificity and adaptive highly specific
- in innate resistance resistance not improved by repeat infection, but is in adaptive
- innate has rapid response (hrs) and adaptive has slower response (days-wks)
What does 2º contact w/ antigen result in?
- enhanced adaptive responses
What are the external barriers to infection?
- keratinised skin –> keratin difficult for bacteria to digest and must be damaged to infect
- secretions –> sebum, sweat, FAs, lactic acid, lysosyme = low pH, dry and salty
- mucous –> cilia in resp tract traps pathogens
- low pH of 2.5 in stomach
What is commensalism?
- 1 organism benefits from another
What are the 3 types of phagocytes?
- neutrophils
- mononuclear phagocytes
- mast cells
What are the characteristics and role of neutrophils?
- main phagocyte in blood
- short-lived
- fast moving
- lysosomes release enzymes (H2O2) etc.
- unusual shaped nucleus
What are the characteristics and role of mononuclear phagocytes?
- monocyte in blood/macrophage in tissue
- long lived (months-yrs)
- help initiate adaptive responses
What are the characteristics and role of mast cells?
- underlying mucosal surfaces in skin
- release inflammatory mediators (eg. histamine)
- important in parasite and allergy response
What are the characteristics of NK cells?
- type of lymphocyte
- kill virally infected cells non-specifically
- important in self/non self recognition and may kill cancer cells
How are pathogens recognised by phagocytes/mast cells? (innate)
- have general pathogen recognition receptors (PRRs)
- that recognise pathogen-assoc molecular pattern (PAMPs)
- eg. Toll-like receptor 4 recognises LPS
How are pathogens recognised by NK cells? (innate)
- kills target unless they recognise self protein (MHCI)
What are the integrated responses to infection/injury?
- inflammation (v beneficial), localised response to infection and damage (dilation of blood vessels, increase in capillary permeability, phagocytes migrate into tissue)
- PAMPS/DAMPS (pathogen/damage assoc mol pattern)
- induces release of inflammatory mediator and prod of cytokines
3 examples of soluble factors
- complement system
- defensins
- interferons
What is the complement system?
- approx 20 proteins in blood
- activated on infection
- bacterial cell lysis
What are defensins?
- positively charged peptides
- made by neutrophils
- disrupt bacterial membranes
What are interferons?
- prod by virally infected cells
- protect uninfected cells
- activate macrophages and NK cells