Adaptive Immunity III: T cells

Question 1

T lymphocyte

Answer 1

One of the two types of antigen-specific lymphocytes responsible for the adaptive immune response. They are responsible for the cell-mediated adaptive immune reactions

Question 2

T cell receptor (TCR)

Answer 2

The cell surface receptor for antigen on T lymphocytes. It consists of a heterodimer of alpha and beta chains.

Question 3

CD8

Answer 3

The co-receptor for T cell receptors that recognise peptide antigens bound to MHCII. It binds to MHCII.

Question 4

CD4

Answer 4

The co-receptor for T cell receptors that recognise peptide antigens bound to MHCI. It binds to MHCI.

Question 5

Cytotoxic or CD8 T cell

Answer 5

T cells that kill other cells that have intracellular pathogens that live or reproduce in the cytoplasm or mutated proteins in the cytoplasm that are recognised as foreign when displayed on MHCI

Question 6

Helper or CD4 T cell

Answer 6

These are the classes of T cells that help activate or recruit other cells of the immune system

Question 7

Somatic (DNA) recombination

Answer 7

DNA recombination that takes place in somatic cells to distinguish it from recombination that occurs in meiosis.

Question 8

Junctional diversity

Answer 8

The variability in sequence present in antigen specific receptors (TCR and BCR) that is created during the process of joining V, D and J gene segments and is due to insertion of nucleotides at the joins between gene segments

Question 9

Positive selection

Answer 9

A process occurring in the thymus in which only those developing T cells whose receptors recognise antigen presented on MHCI or II can mature/ survive

Question 10

Negative selection

Answer 10

The process by which thymocytes that bind self-antigens too strongly (self-reactive) are deleted/killed by apoptosis during T cell development in the thymus

Question 11

TH1 T cells

Answer 11

A subset of effector CD4 T cells that are characterised by the cytokines they produce. Mainly involved in activating macrophages

Question 12

TH2 T cells

Answer 12

A subset of effector CD4 T cells that are characterised by the cytokines they produce. They recruit and activate eosinophils, basophils and mast cells

Question 13

TH17 T cells

Answer 13

A subset of effector CD4 T cells that are characterised by production of the cytokine IL17. They help recruit neutrophils to site of infection

Question 14

TFH (T Follicular Helper) T cells

Answer 14

An effector CD4 T cell found in lymphoid follicles that provides help to B cells for antibody production and class switching.

Question 15

Tregs or regulatory T cells

Answer 15

Effector CD4 T cells that inhibit T cell responses and control immune reactions and prevent autoimmunity. There are different subsets: natural and induced/adaptive

Question 16

Effector T cell

Answer 16

The T cells that perform the functions of an immune response, such as cell killing and innate and B cell activation, that clear the infectious agent from the body

Question 17

Memory T cell

Answer 17

T lymphocyte that mediate immunological memory. More sensitive and more rapidly activated than naïve T cells so respond rapidly on re-exposure to the antigen that originally induced them.