Chapter 16: Interferons and Complement system Flashcards
What cells are involved with Type 1 Interferons?
(1) Leukocytes [alpha interferons] (2) Fibroblasts [Beta interferons] (3) Produces antiviral proteins in neighboring cells
Mechanisms of Interferons: Alpha and Beta
(1) Virus infects (2) Signal sent to host cell nucleus (3) Viral replication activates host cell gene for interferon (4) Interferon is synthesized and released (5) Interferon binds to surface of neighboring cell (6) Cell stimulates antiviral protein and they float around waiting for virus to enter (7) Antiviral protein block viral replication by attaching to virus
Interferons action plan
(1) Interferes with virion replication in other cells (2) Specific to kill uninfected cells NOT already infected (3) Implement production of Antiviral Proteins (AVPs)
Mechanisms of interferon: Gamma
(1) Lymphocytes and NK cells do not have to be infected with virus for synthesis of gamma (2) Helps macrophages rid themselves of viruses (3) Enhances the activity of lymphocytes, NK cells and macrophages
Anti viral proteins works best against what?
RNA
Phagocyte cells (removes debris and pathogens)
Fixed macrophage, Neutrophil, Free macrophage, Eosinophil, Monocyte
Extracellular killing cells (destroys abnormal cells)
NK cells break down abnormal cells and ends in lysis
Multiple effects on inflammation
(1) Blood flow increases (2) Phagocytes activated (3) Capillary permeability increased (4) Complement activated (5) Clotting reaction walls off region (6) Temp increased in region (7) Specific defenses activated
Fever is the rise above what temp?
37 degrees celcius
Interferons are released by what type of cell
Lymphocytes (gamma and do not need to be infected), NK cells macrophages and infected cell
Classical Pathway includes which 3 complements initially and what goes on?
C1, C4, C2 (Antibodies bind to antigens such as microbes)
Alternative Pathway includes which 3 Factors and what goes on?
(1) Properdin pathway: Factor B, Factor D, Factor P (2) Activated earlier than classical (3) Activated by the contact between complement proteins and polysaccharides at the pathogen surface
Which complement factors are involved in inflammation?
C4a, C3a, C5a
Which complement factors are involved in opsonization?
C3b
Which complement factors are involved in membrane attack complexes
C5b, C6, C7, C8, C9
What is the complement system?
(1) Series of reactions leading to death of pathogen (more than 20 regulatory pathogens involved)
Where is the complement system proteins produced?
Produced by the liver and circulate in plasma in an active form
General function of Complement system
(1) Enhance phagocytosis (2) Lyse microorganisms, bacteria and enveloped viruses directly (3) Generate peptide fragments that regulate inflammation and immune response (4) Fast
How does complement system work as a cascade
Works as a cascade because one protein amplifies another protein and stimulates a reaction
Deficiency of protein C3 can lead to what?
Problems with complement system and possibly autoimmune disease
Acute phase response
A response to acute illnesses that involves increased production of a specific blood protein called “acute phase proteins”
After both Classical and Alternative pathway finish what happens next?
(1) C3 and C9 are activated (2) C3 is key component that splits into C3a and C3b which participates in Opsonization, Inflammation and Membrane attack complexes
Opsonization
(1) Counteracts the bacteria that carry M protein which prevents them from phagocytosis (2) Sprinkling pathogen so that it is more recognizable to the macrophage
Opsonins
Bind to act and coat the surface of the infectious agent
