Lecture 13

Question 1

total proportion of T cells in human blood, common cell surface markers and number of lymphocytes per microlitre

Answer 1

75%, CD3, 1500 leukocytes per microlitre

Question 2

total proportion of helper T cells in human blood, unique cell surface marker and number of lymphocytes per microlitre

Answer 2

45%, CD4, 900 leukocytes per microlitre

Question 3

total proportion of cytotoxic T cells in human blood, unique cell surface marker and number of lymphocytes per microlitre

Answer 3

30%, CD8, 600 leukocytes per microlitre

Question 4

total proportion of B cells in human blood, unique cell surface marker and number of lymphocytes per microlitre

Answer 4

12%, CD19 or 20, 250 leukocytes per microlitre

Question 5

total proportion of NK/ADCC cells in human blood, unique cell surface marker and number of lymphocytes per microlitre

Answer 5

15%, CD 16 or 56, 300 leukocytes per microlitre

Question 6

What MHC Class receptor activates antigen-sensitive CD4 Helper T cells?

Answer 6

MHC Class 2

Question 7

what are cytokines made of?

Answer 7

low molecular weight glycoproteins

Question 8

function of cytokines

Answer 8

regulate the quality, amplitude and duration (acute or chronic) of immune and inflammatory reactions, and to influence behaviour

Question 9

where are cytokines produced?

Answer 9

local to the site of injury (paracrine or autocrine, rather than endocrine) - produced transiently (for a short time only when needed)

Question 10

what determines the action of a cytokine?

Answer 10

the concentration, presence of other cytokines, cell type responding, and history of the cell

Question 11

are cytokines only produced by blood cell lineages?

Answer 11

no, some are produced by other cell types

Question 12

what systems do cytokines affect, other than the immune system?

Answer 12

non-immune cellular and system behaviour (e.g. nervous system)

Question 13

what cells produce the most cytokines?

Answer 13

CD4 Helper T cells

Question 14

how are cytokines classified?

Answer 14

based on the role they perform

Question 15

another name for innate response cytokines

Answer 15

pro-inflammatory cytokines

Question 16

function of innate response cytokines

Answer 16

• promote inflammatory processes (increased production cytokines (affected body temperature and sleeping pattern) and chemokines (IL-8)) - e.g. production of antibodies, phagocytosis and inflammation, cytotoxicity
• limit tissue damage
• initiate immune mechanisms (e.g. IL-1 and TNF)

Question 17

examples of adaptive response cytokines and their function

Answer 17

IL4 - controls B cell activation

Interferon-phi/IL-2 - controls T cell activation

Question 18

two main types of CD4 Helper T cells, the cytokines that control them and what they’re important for

Answer 18

Th1 - IFNgamma - intracellular infections

Th2 - IL-4 - parasitic responses

Question 19

function of chemokines (chemotactic cytokines)

Answer 19

promote neutrophil chemotaxis at sites of inflammation

IL-8

Question 20

function of haematopoietic cytokines

Answer 20

stimulate the production of various classes of blood cells (neutrophils, erythrocytes, monocytes, lymphocytes) from bone marrow when needed (e.g. GM-CSF = granulocyte-macrophage-colony stimulating factor)

Question 21

function of co-stimulator molecules

Answer 21

modulates the actions of lymphocytes when they recognise antigens

Question 22

example of a co-stimulator pair, the corresponding signal 1 and 2’s and the result (pg 69)

Answer 22

• B7 (CD80 and 86 - on activated APC’s, i.e. only appears when the antigen presented on the MHC receptor is foreign and potentially dangerous) and CD28 (on T cells).
• Signal 1 = activation of TCR complex by antigen on MHC Class I or II
• Signal 2 = binding of co-stimulators B7 (CD80 & 86)
• Signal 1 + 2 = activation of T cell (clonal expansion)

Question 23

TCR complex constitutes of what?

Answer 23

TCR, T cell, CD4/8

Question 24

what’s a safety mechanism to prevent autoimmunity?

Answer 24

co-stimulators (e.g. B7 on APCs and CD28 on T cells) needing to bind to cause activation of the T cell, if this binding doesn’t occur then the T cell is paralysed - this is called anergy and protects the immune system from reacting against self. (lymphocyte must have B7, regardless of whether it has an antigen on the MHC class I/II structure