B and T Cells and Cytokines Flashcards
how do cells communicate?
cell-cell contact, signalling via receptors - ligand interactions between membranes of different cells e.g MHC and TcR
what are cytokines?
- small polypeptides
- released by cells in response to activating stimulus
what 3 behaviours can cytokines exhibit?
autocrine: effects on cell that secretes it
paracrine: effects on adjacent cells
endocrine: effects on distant cells
what are chemokines?
a class of cytokine that has chemoattractant properties: - induces cells to migrate towards source
what are interleukins?
cytokines secretes by leucocytes
what are the two main groups of chemokines?
- CC (binds ro CCR1-9)
- CXC (binds to CXCR1-5)
what does IL-8 do?
chemotactic factor that recruits neutrophils and T cells to site of infection
what does IL-2 do?
- activates T cells -
- induces self proliferation
what does IL-4 do?
- activates B cells
- switches them to produce IgE, therefore important in allergy
what does IFN-γ do?
- activates strong cell mediated responses
what does TNF-α do?
- activates vascular endothelium and increases vascular permeability
by what process do neutrophils access infection sites?
diapedesis
what are the steps for a neutrophils entering infection sites?
- rolling adhesion
- tight binding
- diapedesis
- migration
upon release, what does TNF-α trigger, and what can it induce?
- triggers local protection
- can induces systemic shock
name the two types of CD4 T cells?
Th1 - produce cell mediated immunity
Th2 - produce antibody responses
what are dendritic cells (DC)?
professional antigen presenting cells that sits at the interface between innate and adaptive immune response
what are functions/features of dendritic cells?
- found in most surface epithelia
- highly phagocytic
- upon stimulation, cease phagocytosis and migrate to lymph nodes
what are other names dendritic cells are known by?
- langerhans cells in skin
- interdigitating cells
- follicular dendritic cells (FDC)
- veiled cells when migrating in circulation
what do DC cells in lymph nodes do?
- activate T cells
- influence B cells
what are features of FDCs?
- can hold on to antigen for extended periods
- antigen in form of antigen-antibody -complement complexes
- complexes do not appear to undergo internalisation
what do DC express?
pattern recognition receptors (PRR)
