B and T cells and cytokines Flashcards
What are cytokines?
Usually small polypeptides, around 25000 Mr released by cells in response to an activating stimulus
What are chemokine?
A class of cytokine that has chemoattractant properties, i.e. induces cells to migrate towards the source
What are interleukins?
Cytokines secreted by leucocytes
What are the two main groups of chemokine?
- CC which binds to CCR1 to 9
* CXC which binds to CXCR1 to 5
How are the main groups of cytokines named?
Due to spacing of cysteine residues close to amino terminus
IL8
Chemotactic factor, recruits neutrophils and T cells to the site of infection
IL2
Activates T cells, proliferation
IL4
Activates B cells which switches them to produce IgE therefore important with allergy
IFN- gamma
Activates strong cell mediated response e.g. CTL
TNF-alpha
Activates vascular endothelium and increases vascular permeability
IL1
- Activates the vascular endothelium and lymphocytes
- Local tissue destruction
- Increases access of effector cells
- Leads to Fever and production of IL6
How do neutrophils access infection sites?
Diapedesis
What can TNF alpha induce which can be harmful?
Systemic shock
What are the two types of CD4 T cell?
- TH1 : produce cell mediated immunity- active macrophages, B cells and causes the production of opsonising antibodies such as IgG1
- TH2 produces antibody responses: general of B cells to make antibodies
What do activated Th1 cells do?
- IFN-gamma and CD40 ligand: Activates macrophage to destroy engulfed bacteria
- Fas ligand: Kills chronically infected macrophages, releasing bacteria to be destroyed by healthy macrophages
- IL-2: Induces T cell proliferation, increasing the number of effector T cells
- IL3: Induces macrophage differentiation in the bone marrow
- LT and TNF alpha: Activates endothelium to induce macrophage adhesion and exit from blood vessel at the site of infection
- MCP: Causes macrophages to accumulate at the infection site
