The Innate Immune System Flashcards
What are the direct methods of harm used by pathogens
Exotoxin - mostly neurotoxins which leave cells intact but damage host nervous system
Endotoxin - colonies cells and produce endotoxin
Direct cytopathic effect - borrow cell mechanisms: virus
What are the indirect methods of damage used by pathogens
Immune complexes - coagulation
Anti-host antibodies - attack our antibodies
Cell mediated immunity comes
What is the bodies first line of defence
Skin, mucus membrane, Collins, hairs
Innate immune system
What is the bodies second line of defence agains pathogens
Inflammatory response
Innate immune system
What is the bodies third line of defence
B & T lymphocytes, antibodies
Adaptive immune system
What is innate immunity
Present in all multicellular organisms
Non-specific - always present in inactive form
Non-adaptive - doesn’t develop memory
It is rapid, strong and aims to quickly eliminate agent
It doesn’t amplify response with repeated infections
What are the main functions of the innate response
Barrier against free entrance of organisms (physical, chemical, mechanical)
Modulate immune response
What cells are involved in the innate immune system
Myeloid cells - dendritic, platelets, monocytes, macrophages, mast cells
Lymphoid cells - natural killer cells
What is the function of phagocytise cells
Engulf the antigen
Neutrophils
Weak phagocytes
Present in early inflammatory response
Produced mainly in bone marrow
6hr life span. Non-recruited cells destroyed in spleen or liver
Macrophages
Strong phagocytes Bind to opsonins Late inflammatory response (weeks) Produced mainly in bone marrow - derived from monocytes Average life - weeks after recruitment
Dendritic cells
Primary orchestrator of immune system
Rare but highly effective
Immature captures antigen, mature’s after capturing and processing the antigen into cell surface.
Carries antigen to lymph node for action to be determined
How are microbial particles recognised
Damaged cells release histamine which diffusers into capillaries
Histamine causes vasodilation of capillaries which become leaky
Complement proteins attract phagocytes
Plasma and phagocytes engulf Bacteria and dead cells
Histamine and compliment signalling cease; phagocytes are no longer attracted, tissue returns to normal
How to neutrophils / macrophages recognise microbes
Toll receptors
Antibodies via FC receptors
Opsonins via antibodies / FC receptors
Interferon
What occurs at toll receptors
Toll like receptors in cell surface recognise non-native patterns on a cell surface e.g LPS.
These are then taken inside then phagocytosed
Recognition, uptake, processing
