Innate Immune System Flashcards
What are the two types of responses to pathogens?
Cellular and humoral (in solution).
Which two cell types are involved in the allergic response and what do they secrete?
Mast cells, Basophils secrete histamine.
Which cell types are involved in the cellular response?
Phagocytes (Neutrophils and macrophages), Natrual Killer cells and Eosinophils.
What is the name of the system that comprises most of the humoral system?
Complement system
What is the complement sytsem comprised of and where does it exist?
Proteins within the blood
How does the complement system kill bacteria?
Once the membrane proteins are activated complexes form tha punch a hole in the surface of the microbe.
What are the 3 complement activation pahtways?
Classical, alternative, mannose-binding lectin pathway
Which innate system cell type is a lymphocyte in the same family as T and B cells?
Natural Killer Cell
The natural killer cell can be identified by which clusters of differentiation (CD) ?
CD3 negative and CD56 positive.
Which type sof pathogens are natural killer cells particularly known for combatting?
Virally infected cells and detecting and controlling early signs of cancer.
Natural killer cells can enhance the immune response by secreting whihc cytokines and subseqeuntly acting on whihc type of immune cells?
IFN gamma and TNF alpha, which act on macrophages and dendritic cells.
How does the activation mechanism of NK cells work?
Whilst patrolling NK cells constantly in contact with other cells. Killing depends on balance of activating and inhibatory receptors on the NK surface. Normal healthy cells express enough MHC class 1 molecules to induce a strong inhibatory signal.
Tumour cells and infected cells often downregulate the MHC class 1 molecules thus a weakened inhibatory signal. They also sometimes increase the expression of molecules recognised by activating NK cell receptors. This may override the inhibatory signal and allow killing.
What is the killing mechanism of NK cells?
The release of cytotoxic granules containing perforin and granzymes which leads to the lysis of the target cell.
Genes for both MHC I and the NK cell inhibatory receptors which recongise them vary a lot between individuals, what is the consequence of this?
The versions of these genes a person carries have been linked to thier ability to fight HIV infection and their risk of autoimmune diseases.
