Antigen recognition by lymphocytes I

Question 1

How is specificity achieved for antigen recognition?

Answer 1

Antigen receptor on cell surface

Question 2

What is a B cell’s receptor?

Answer 2

cell-surface antibody

Question 3

What is a T cell’s receptor?

Answer 3

T cell receptor

Question 4

Immunoglobulins are synthesised and secreted by what?

Answer 4

B cells

Question 5

To secrete Ig, B lymphocytes must be actiavted by a binding agent, what do they differentiate into after this?

Answer 5

Plasma cells

Question 6

T cell independant antigens only produce what in small amounts?

Answer 6

IgM antibodies

Question 7

T cell receptor recognises antigen in form of what?

Answer 7

A complex of foreign peptide bound to a MHC molecule

Question 8

What is a TCR?

Answer 8

Very similar to the fab fragment of an antibody but not identical

Question 9

Majority of cells have alpha beta TCR. What types may be specialised to bind to ligands such as heat shcok proteins, nonpeptide ligands, phosphorylated ligands and mycobacterial lipid antigens?

Answer 9

gamma,delta TCR

Question 10

Antigenic peptides recognised by two different TCR are seen to be from theh interior or exterior of the molecule?

Answer 10

Interior

Question 11

T cells fall into two major classes. Name these and how they are distinguished by the expression of CD8 or CD4 proteins

Answer 11

Helper- CD4 + CD3

Cytotoxic- CD8 + CD3

Question 12

CD4 also makes contact with what?

Answer 12

MHC on antigen presenting cell

Question 13

Adhesion molecules LFA-1 and ICAM-1 also form adhesive interactions between T cells and APC. Describe the binding process and effects of these molecules

Answer 13

T cells initially bind APC through low affinity LFA-1-ICAM-1 interactions

Subsequent binding of Tcell receptor signals LFA-1

Conformational change in LFA-1 increases affinity for ICAM-1 and prolongs cell-cell contact

This leads to T cell activation

Question 14

Pairing of accessory molecules has what affect?

Answer 14

Stabilises interaction and provided co-stimulation

Question 15

APCs deliver three kinds of signals to naiive T cells. What are these signals?

Answer 15

Activation
Survival
Differentiation

Question 16

After binding antigen, CD4+ T cells secrete cytokines which control and coordinate immune response. What are these responses?

Answer 16

Some secrete cytokines that:
Favour macrophage activation and cell-mediated responses
Other that stimulate B cells to produce antibodies

Question 17

TCR/MHC Class I/CD3/CD8 form what?

Answer 17

Complex bridges between virally infected cell and cytotoxic T cell

Question 18

The receptor for antigen on a B cell (BCR) is a form of what?

Answer 18

Form of the antibody it is programmed to make

Question 19

Lymphocytes are activated by binding agent, which triggers them to form what?

Answer 19

A clone of antigen-specific cells