Lecture notes
CD4+ T Cells and their role in immunity
- Module
- Immunology
- Institution
- Bournemouth University Talbot Campus (BUTC)
Lecture notes detailing CD4+ T cells and what roles they play in immunological processes
[Show more]
Seller
Follow
Content preview
Lecture 12 – CD4+ T Cells, Key Regulators ofImmunity
Life History of T Lymphocytes
- Precursors mature in the thymus.
- Naïve CD4+ and CD8+ T cells enter the circulation.
- Naïve T cells circulate throughout the lymph nodes and locate antigens.
- Activation of naïve T cells in the lymph node, development of effector cells.
- Activation of effector T cells at the site of infection, eradication of the microbe.
Naïve T Cell Signals Required
Signal 1
For CD4+ T cells –
- Interaction with MHC II/peptide complex.
- CD4 binds with MHC Class II.
- Signalling by CD3 on the T cell.
- Usually supplied by a professional APC.
For CD8+ T cells-
- Interaction with MHC I/peptide complex.
- CD8 binds to the MHC Class I.
- Signalling by CD3 on the T cell.
- Can be supplied by most nucleated cells.
Signal 2
Co-stimulation
- Lots of potential receptor/ligand interactions.
- APC dictates what the T cell should do.
- Determines T cell activation.
- Also qualitative:
o Tells the T cell what response to make.
o Make cytokines or not?
o What kind of cytokines?
o How much killing?
o How many divisions should I complete?
Antigen-Presenting Cells
Professional APCs constitutively express MHC class I and II.
Non-professional APCs (like keratinocytes) can upregulate MHC Class II in response to IFN-
gamma.
Professional APCs are very responsive to pattern recognition receptors or other
inflammatory signals.
PRRs/inflammation leads to the upregulation of co-stimulatory ligands.
, Dendritic cells are major APCs of the body:
- APCs are master regulators of the immune system Controls T cells T cells control B cells.
First Step in Adaptive Immunity: Dendritic Cell Maturation
- DC requires presence of antigen and evidence of danger/pathogen to be fully active.
- DC maturation and migration occurs at the same time.
Immature Dendritic Cells
Decrease co-stimulatory molecules.
Decreased MHC Class II expression.
Decreased secretion of pro-inflammatory cytokines.
Increased phagocytic capacity.
Decreased CCR7 expression.
Decreased glycolysis.
Pathogens, cytokines, PAMPs, DAMPs
Mature Dendritic Cells
Increase co-stimulatory molecules.
Increased MHC Class II expression.
Increased Secretion of pro-inflammatory cytokines.
Decreased phagocytic capacity.
Increased CCR7 expression.
Increased glycolysis.
B7-CD28: A Co-stimulatory Molecule
B7 is expressed on resting DCs but increased by activation.
Signals via CD28, tells the cell along with CD3:
- Divide.
- Do not die.
- Differentiate.
Other Co-stimulatory Interactions
- CD28/B7 is well studied and has many interactions.
- The key ones are 4-1BB/OX40/CD27.
- Not clear why there’s so many but may be:
o Activate with delayed kinetics.
o Qualitative differences.
o Different effects on different T cell subsets.
4-1BB preferentially activates CD8+ T cells, OX40 prefers CD4+ T cells.
Dendritic Cell Licensing
DC activates CD4+ T cell but it is a 2-way interaction.
Activated CD4+ T cell signals to DC via CD40.
Further activates the DC to provide additional signals to other cells.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller biomedicalscience4. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £7.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75632 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now