Immune Recognition

Question 1

What are the wo types of recognition molecules and what types of immunity are they responsible for?

Answer 1

1. B cells- Humoral/Antibody Immunity
2. T cells- Cell Mediated immunity

Question 2

Describe the B-cell receptor

Answer 2

-Y shaped with a variable and constant domain
-4 chains (2 heavy, 2 light)
- Hinge region made of disulfide
-Antigen binding site on the end of the y shape in the variable domain

Question 3

What is the importance of the hypervariability in the variable domain of the receptor B cell receptor?

Answer 3

This allows recognition of specific antigens. When there is specific interaction between the epitope and the combining site on the receptor it generates a high affinity response that would result in the appropriate immune response for the antigen

Question 4

Explain BCR complex clustering

Answer 4

For a B cell receptor to generate a immune response some factors must be met. There must be high affinity binding in the variable region on the cell receptor which will then trigger IG alpha and beta which signal to the B cell to begin t make daughter cells. However the b cell can only generate daughter cells if the clustering is satisfied. This occurs when at least 2 B cells are both binding to the same type of epitome from the same pathogen. This creates the cluster needed for the B cell to be activated and proliferate

Question 5

T cells require ____________ information of the _______ which can be presented in two ways ____ _________ which is due to viral infections and interacts with ______ T cells to kill viruses and ____ _________ which interacts with ______ T cells.

Answer 5

processed
pathogen
MHC Class 1
CD8
MHC Class 2
CD4

Question 6

Which MHC class do the following peptides bind to

1. Cytosolic pathogens
2. Intra vascular Pathogens
3. Extracellular pathogens and toxins

Answer 6

1. MHC Class 1
2. MHC Class 2
3. MHC Class 2

Question 7

What type of cells don’t express MHC Class 2

Answer 7

Nucleated cells and red blood cells/

Question 8

What type of cells don’t express MHC Class 1

Answer 8

Red blood cells

Question 9

Summarize the MHC Class I processing and presentation pathway

Answer 9

1. Peptide Antigen generation: An intracellular antigen’s peptide is trimmed by a proteosome
2. Transport: The peptide trimmings are then transported via TAP molecules into the endoplasmic reticulum
3. Assembly of the MHC Loading Complex: The MHC complex is assembled using 4 chaperone proteins (calreticulin, tapsin, calnexin, thiol oxidoreductase)
4. Antigen Presentation: Peptide bind to the MHC loading complex and chaperones are released. The MHC class I and antigen leave the ER via the golgi apparatus and migrate to the surface of the cell membrane where MHC class 1 will be recognised

Question 10

Summarize the MHC Class II processing and presentation pathway

Answer 10

1. Antigen is acquired via endocytosis (phagocytosis/pinocytosis)
2. The antigen is transported in a vesicle
3. The antigen is proteolytically degrade within the vesicle

4.The CLIP (Class II associated invariant-chain peptide) that was previously bound to the MHC class II groove is removed by HLA

5. The antigen binds to MHC Class II
6. The now formed complex leaves the multivesicular body and is inserted into the cell membrane for recognition