MHC molecules

Question 1

MHC II normally only expressed

Answer 1

on cells of the immune system

Question 2

MHC IIespecially expressed on

Answer 2

B cells, macrophages and dendritic cells

Question 3

MHC II bind

Answer 3

to peptide generated from internalised antigen in the endosomal compartment of cells

Question 4

Antigens derived form internalised microognism by lysosomal proteases displayed by MHC class II molecules on dendeiritc cells are recognised by

Answer 4

naive T cells at the initiation of immune response

Question 5

two classes

Answer 5

CD8 and CD4

which monitor different internal compartments f cell and are recognised by distinct classes of T cells

Question 6

how does the Dendritic/ T cell interaction look:
MHC class I

Answer 6

• CD8T cell
• which has a CD8 co-receptor
• MHC class I molecule only has one transmembrane parts

Question 7

how does the Dendritic/ T cell interaction look:
MHC class II

Answer 7

• CD4T cells
• which has a CD4 co-receptor
• MHC class II has 2 parts which are transmembrane

Question 8

MHC I

Answer 8

expressed on all body cells and bind peptides generated by cytoplasmic proteases from cytoplasmic proteins

Question 9

difference between MHC I and II

Answer 9

MHC I- present on all cells and binds peptides generate day cytoplasmic proteases

MHCII- only present on immune cell. Bind to peptide generated internalized antigen it he endosomal compartment of cells

Question 10

critical role of MHC I

Answer 10

• to display antigens derived from pathogens which replicate in the cytoplasm and antigen displayed on MHC class I molecules is recognised by cytotoxic T cells- kills infected cell
• Ensures destruction of cells in which cytoplasmic pathogens are replicating – essential for elimination of some pathogens

Question 11

which specialised WBC is responsible for eliminating unwanted body cells e..g cancers and kills cells infected with influenza

Answer 11

Cytotoxic T cells

Question 12

recognition of antigen and MHC class I molecules by cytotoxic T cells

Answer 12

peptide fragments of pathogens such as viruses that replicate in the cytoplasmic compartments of cells are carried to the cel surface by MHC class I molecules and recognised by cytotoxic T cells

Question 13

upon activation, CD8 t cells (cytotoxic T cells) produce

Answer 13

perforins and granzymes

Question 14

perforins

Answer 14

proteins that form pores in the membrane of target cells

Question 15

granzymes

Answer 15

proteases that induce programmed cells each on entry into target cells
- similar to how apoptosis occurs

Question 16

monitoring of internal compartments- what are the two internal compartments of a cell

Answer 16

the cytoplasm

Vesicles of endosomal/lysosomal pathway

Question 17

the cytoplasm contains

Answer 17

all viruses and some bacterial pathogens replicated in the cytoplasm

Question 18

Vesicles of endosomal/lysosomal pathway

Answer 18

contain internalised antigens derived from extracellular pathogens

Question 19

why is it important that internalised compartments are monitored

Answer 19

In specialized cases of macrophages, vesicles may harbor bacteria and some fungi, adapted to survive phagocytosis

Question 20

Cytoplasm is monitored by

Answer 20

MHC class I molecule

Question 21

Vesicular compartments are monitored by

Answer 21

MHC class II

Question 22

Recognition of antigen and MHC class II molecules on macrophages by helper T cells

Answer 22

• Helper T cells recognise fragments of a pathogen that has been internalized by macrophages and have undergone proteolytic digestion to generate fragments that are carried to the cell surface by MHC class II molecules.
• The helper cell is then stimulated to activate the macrophage to destroy the internalized pathogen.
• This is particularly important for defense against bacteria that are able to grow in the internal vesicles of macrophages

Question 23

Recognition of antigen and MHC class II molecules on B cells by helper T cells

Answer 23

B cells internalise antigens bound to their surface immunoglobulin and deliver them to the endosomal compartments of the cell where they are digested into fragments.
-	The antigen fragments then bind to MHC class II molecules which carry them to the cell surface where they are recognised by  helper T cells, which then activate the B cell to proliferate and  differentiate into an antibody- secreting plasma cell