Adaptive immunity - part 1

Question 1

What is the role of T cells?

Answer 1

1. Identify antigens that are presented to them by antigen presenting cells (macrophages and dendritic cells)
2. present antigen to B cells (T-cell help)

Question 2

What is the role of B cells?

Answer 2

To recognise antigen specific T cells
To produce antibodies specific to the t cell antigen
To proliferate (clonal expansion)

Question 3

Which globulin group do antibodies (immunoglobulins) belong in?

Answer 3

Gamma globulins

They are the right most wave on an electrophoresis assay.

Question 4

What are the 2 regions of an antibody?

And are antibodies the same as a T cell receptor?

Answer 4

Constant region - found on the base of the ab)
Variable region - the part which binds antigen (found on the tips of the ab)
Antibodies and TCRs are the same, but only antibodies are secreted.

Question 5

Where is an Fc receptor found?

Answer 5

Various immune cells eg. macrophages.

The purpose of the Fc receptor is to bind to the constant region (Fc region) of an antibody.

Question 6

What is the major immunoglobulin?

Answer 6

IgG - It removes pathogens from the blood and tissues

Question 7

2 examples of what an Fc region on an antibody can bind to?

Answer 7

1. complement proteins bind to the Fc region, to form a membrane attack complex to kill a pathogen
2. opsonisation - fc region binds to receptors on macrophages, and provides an ‘eat me’ signal

Question 8

Describe the structure of IgA

Answer 8

2x IgA molecules joined together at their tails by a J protein

Question 9

What is secreted to fight mucosal infections?

Answer 9

IgA - it is secreted across epithelial surfaces

Question 10

Which cells do IgE bind to?

Answer 10

Binds to receptors on mast cells and eosinophils.

Question 11

Which immunoglobulin defends against parasites and is also involved in allergies/asthma?

Answer 11

IgE -
These bind to eosinophils which have parasite damaging granules
They also bind to mast cells, which release histamine

Question 12

What are the 2 main types of T cell?

Answer 12

Cytotoxic T cells (CD8+) - these recognise infected cells and kill them
Helper T cells (CD4+) - help a B cell to make antibodies

Question 13

Which disease causes destruction of helper T cells?

Answer 13

HIV

A pt will have a low T helper cell count, and a very poor B cell antibody response