Innate Immunity Flashcards
What is the difference between the innate and adaptive immune system?
Innate: non-specific, immediate
Adaptive: specific, delayed
What are the main factors involved in innate immunity?
Epithelial barrier with tight junctions
Mucus
Enzymes
Phagocytosis
Complement system
How is mucus effective?
Trap bacteria so they cannot adhere to surface
What are the steps of phagocytosis?
Phagocyte recruited by chemokines and complements
Phagocyte binds to pathogen
Pathogen is internalised to phagosome
Phagosome fuses with lysosome
Pathogen destroyed by nitrous oxide
5 examples of antibacterial peptides?
Alpha Beta defensiva
Lysozyme
Lactoferrin
Phospholipase A
Histatins
What are 3 ways of activating the complement cascade?
- Classical
- MB lectin
- Alternative
What are the 3 outcomes of the complement cascade?
- Recruitment of inflammatory cells
- Opsonisation of pathogen
- Killing of pathogen via lysis
What is the classical pathway activated by?
C1q interacts with antibody:antigen complex
What is lectin?
Carbohydrate binding protein
Why can lectin bind to microbes?
Mannose in microbes cell surface
How is the MB lectin pathway initiated?
MB lectin binds to mannose
How is the alternative pathway initiated?
C3 cleavage
What are the actions of C3a and C5a
Inflammatory mediators
What are the inflammatory mediators effects?
Increase vascular permeability
Increased fluid leakage
Migration of macrophages, PMNS and lymphocytes increased
Microbicidal activity increased
What is chemotaxis?
Movement of cell down a chemical gradient
Low-high concentration
How do microbes hide?
Evolved capsules
What is opsonisation?
Coating of a particle with proteins
Facilitate phagocytosis by macrophages or dendritic cells
What immune cells are associated with innate immunity?
Myeloid cells
Granulocytes, monocytes, macrophages, and dendritic cells
What lymphoid cells are associated with innate immunity?
Natural killer cells
Mature dendritic cells
What granulocytes exist in blood?
Neutrophils
Eosinophils
Basophils
Monocytes
What are the innate immune cells in tissues?
Mast cells
Macrophages
How many cells/litre are there of neutrophils?
5x10^9
What % of total WBCs are neutrophils?
75%
What are the types of phagocyte cells?
Neutrophils
Monocytes/macrophages
Dendritic cells
How do we recognise pathogens?
Opsonisation
PRRs - pathogen recognition receptors
What are 2 examples of PRRs?
Toll like receptors
C type lectins
What are the 3 outcomes of a PRR recognising a pathogen?
Phagocytosis
Secretion of inflammatory mediators
Secretion of cytokines
What are cytokines?
Small glycoproteins
Used in cellular communication
What do pro inflammatory cytokines do?
Activate macrophages
Stimulate inflammatory mediators release
Activate adaptive immune system
What are examples of pro inflammatory cytokines?
Interleukins a and b
TNFa
Interferon g
What do anti inflammatory cytokines do?
Antagonistic to pro inflammatory cytokines
Mediate adaptive immune response
IL 4 & TGF b
What do growth factors do?
Develop immune cells
Stimulate growth and proliferation
What do chemokines do?
Recruit immune cells
What cytokine is produced by all cells in response to viral infection?
Type 1 interferons
Shut down protein and DNA synthesis
Activate immune cells to destroy infected cell
What is the timeline of infection?
Physical barrier
Humoral components: complement, antimicrobiano peptides
PRRs
Recruitment and activation of phagocytes
Activation of adaptive immunity
