The innate immune response Flashcards
What are cytokines?
Secreted by immune cells and affect the behaviour of nearby cells with corresponding receptors.
What are the general properties of cytokines?
- secrete a brief event
- actions are pleiotropic (multiple biological reactions) and redundant (shared biological actions)
- influence synthesis and actions of other cytokines
- the cellular response to most cytokines is a change in gene expression in the target cells, resulting in new functions or proliferation of target cells.
What is a cytokine storm?
Elevated levels of circulating cytokines and immune cell hyper-activation. Causes excessive inflammation that can lead to organ failure and disseminate intravascular coagulation.
What are some important cytokines?
IL-1beta = activates vascular endothelium, lymphocytes, increases access of effector cells and local tissue destruction. Causes fever.
IL-12 = activates NK cells and induces differentiation of CD4 T cells into Th1 cells.
IL8 (CXCL8) = chemo static factor recruiting neutrophils, basophils and T cells.
TNF-alpha.
What are chemokines?
They are chemo attractors - they attract particular cells to the area. For example, if you were cut by a rusty nail, chemokines would send leukocytes particularly neutrophils to the area.
What is the effect of cytokines secreted by macrophages?
Inflammation is important for the return of homeostasis. Creates a fever. Has an acute response and acts on the liver.
Fever raises body temp so bacteria cant grow in hotter temperatures.
What are NK cells?
What are antimicrobial peptides?
part of the innate immune system and they are very small and are good against bacteria fungi and parasites. They destabilise the lipid bilayer causing a pore and water to flood in and lyse the cell (amphipathic).
They can be produced in epithelium within the crypt and in the Paneth cells.
Why do we need to need to keep a healthy gut microbiome?
There is only 1 cell thick lining what we consume in the gut and the rest of our bodies, so we need to ensure a healthy microbiome and a good environment and that there is sufficient information being passed between the microbiome and immune system.
What is inflammation?
It is the brining of cells and molecules via blood to the site of infection. There is an increased blood supply, increased vascular permeability. It helps bring nutrients to the site too as its an energy exhausting process. it is triggered by PRR (pathogen recognition receptors) on the host and PAMP on the pathogen. Tissue damage, also disruption or inappropriate immune response such as autoimmunity (attack our own cells) or an allergy.
What is endotoxic shock?
caused by excessive cytokine release in a gram neg bacterial infection. It has widespread effects on vascular endothelium and causes circulatory shock and disseminated intravascular coagulation (DIC)>
What are mediators of inflammation?
Complement products (C5a and C3a)
Macrophage/ T-cell derived cytokines
mast cells (histamine release)
Give an example of local inflammation:
Gram neg bacteria from a cut to the hand:
- pathogen recognition receptors on the macrophage are stimulated
- release of TNF-alpha but it is controlled
- positive outcome
Give an example of systemic inflammation?
It is toxic shock. say the gram neg bacterial infection has spread into the blood. The PRR on the macrophage are stimulated, TNF-alpha is released but uncontrolled and there is a negative outcome.
What are GI host- immune reactions?
- tight junctions between cells
- saliva, bile, pH, peristalsis
- microbiome helps supress colonisation of pathogens
