Lecture 4 - MHC and Antigen recognition by T cells Flashcards
What is the growth cycle of T-cells?
- Originate in the bone marrow
- Differentiate to mature T-cells in the thymus
- Migrate to the lymphoid tissues
What is the growth cycle of B-cells?
- Originate in the bone marrow
- Differentiate to B-cells in the bone marrow
- Migrate to the lymphoid tissues
What were the adverse effects that Thymectomised mice suffered? [3]
- Susceptibility to viral infection
- Reduced lymphocytes
- Immuniodeficiency
True or False? As we age our Thymus gets bigger and works better.
False. It gets smaller and declines in function.
How do B-cells recognise antigens?
- Express cell surface IgM and IgD.
- Gains specificity by varying the variable regions
Describe the structure of a T-cell receptor.
- Contains an alpha and beta chain
- The alpha and beta chains are held together by di-sulphide bonds
- Has a constant and variable region
What is the role of CD3 on the T-cell receptor?
Interacts with the receptor to mediate intracellular singalling
How do T-cell receptors recognise antigens?
The antigen has to be processed and presented to them via a Major Histocompatibility Complex (MHC)
What is a MHC?
A collection of genes within a long continuous stretch of DNA.
What are the classes of MHC? [3]
- MHC class I
- MHC class II
- MHC class III
Where are MHC I expressed?
Glycoproteins expressed on all nucleated cells
What is the role of class I MHC?
Involved in T-cell recognition of antigen (Tc)
What part of the loci codes for MHC I?
A, B, and C regions
What is the role of MHC II?
Involved in T-cell recognition of antigen (Th)
Where is MHC II expressed?
Glycoproteins on antigen presenting cells
What part of the loci codes for MHC II?
DP, DQ, and DR regions
What are MHC III?
Various proteins that may or may not have immune function
Give three examples of MHC III.
- Tumor necrosis factor
- Heat shock proteins
- Components of complement
Which of the three classes of MHC are involved in antigen presenting to T-cells?
Classes I and II
How does MHC I process antigens?
Intracellularly
Where does MHC II process antigens?
Extracellularly
What happens once an antigen is in an MHC?
T-cell receptor binds to both the antigen and the MHC
Which class of MHC does CD4 recognise?
Class II
Which class of MHC does CD8 recognise?
Class I
