Communication Between Immune Cells Flashcards
Cytokines function
Mediate communication between cells of the immune system
Bind to specific receptors on target cells
Generally soluble
How do cytokines work?
Inducing stimulus causes cytokine-producing cell to produce cytokines
Cytokines bind to receptor on target cell
Gene activation
Leads to desired biological effects
What is autocrine action of cytokines?
Cytokines produced and bind to receptor on same cell
What is paracrine action of cytokines?
Cytokines produced and bind to receptor on nearby cell
What is endocrine action of cytokines?
Cytokines produced
Enter circulation
Bind to receptor on distant cell
Define pleitropy (cytokines)
One cytokines has several different functions
Define redundancy (cytokines)
Several cytokines can perform same function
Define synergy (cytokines)
Cytokines work together
Define antagonism (cytokines)
Cytokines inhibit action of other cytokines
Which cells produce the majority of cytokines?
T helper cells
Dendritic cells
Macrophages
Describe T cells
Part of adaptive immune response
Mature in thymus and migrate to secondary lymphoid tissue
Express T cell receptors which recognise processed antigens present on surface of APCs (macrophages, dendritic cells, B cells)
Differentiate into CD4+ TH cells or CD8+ cytotoxic T lymphocytes
TH1 cell function
Recognises complex of peptide antigen with MHC class 2 and activates macrophage
TH2 cell function
Recognises complex of peptide antigen with MHC class 2 and activates B cell
What drives T helper cell differentiation?
Cytokines
List 5 types of cytokines
Interleukins (IL)
Tumour necrosis factors (TNF)
Interferons (IFN)
Colony stimulating factors (CSF)
Chemokines
Where do interleukins act?
Between leukocytes
IL-1alpha, IL-1beta and IL-6 function
Pro-inflammatory (also TNF alpha)
IL-10 and IL-4 function
Anti-inflammatory (also TGF beta)
IL-2 function
T cell proliferation and differentiation
IL-4 function
B cell activation and differentiation into antibody-secreting plasma cells (Ig class switching)
IL-5 function
Activation of eosinophils
Describe type 1interferons and how they work
First line of defence in viral infections
Interferon alpha and beta
Up-regulation of MHC class 1 presentation
Activation of cytotoxic CD8 response
Destruction of viral RNA
Inhibition of protein synthesis
Describe type 2 interferons and how they work
Interferon gamma
Key cytokines in TH1 immune response
Activation of macrophages
Up-regulation of MHC expression
Clearance of intracellular pathogens
How do colony-stimulating factors work and name 3 subtypes
Mediate growth and differentiation of immature leukocytes in the bone marrow
M-CSF = macrophage CSF
G-CSF = granulocyte CSF
GM-CSF = macrophage/granulocyte CSF
Define chemotaxis
Cell movement directed by soluble factors
What are chemokines and what do they do?
Small cytokines
Induce movement of leukocytes along concentration gradient
Effect of cytokine storm on body
Dilation of blood vessels
Leakage of fluid into body tissues
Perturbation of blood supply
Tissue injury
Widespread blood clotting
Organ failure
Symptoms of cytokines storm
Fever
Circulatory collapse
DIC
haemorrhaging necrosis
Multiple organ failure
How is type 2 diabetes related to cytokines?
Expression of TNF alpha by adipose tissue of obese individuals
Decreased cellular response to insulin and glucose uptake
How is cancer related to cytokines?
IL-6 over-expression in most types of tumours
Enhanced proliferation, angiogenesis, invasive need and metastasis
Increased metabolism —> cachexia
Risks of medications that reduce cytokines activity
Increased risk of infection and malignancy
Risk of very short half life of cytokines in medications
Frequent administration
Risk of pleiotropic action of cytokines in medications
Unpredictable and severe side effects
