Cell mediated immunity

Question 1

T-cells are selected in the thymus based on what two factors?

Answer 1

If they’re able to see MHC

If they’re able to see self

Question 2

What is MHC? What are the 2 classes?

Answer 2

Major histocompatibility complex (glycoprotein)
Class I or class II

Question 3

Which cells express MHC class I on their surface?

Answer 3

All nucleated cells

Execptions: RBCs, platelets and nerve cells

Question 4

Which cells express MHC class II on their surface?

Answer 4

Antigen presenting cells (APCs)

Question 5

What are the functions of MHC class I and II?

Answer 5

Transport samples (peptides) of intracellular proteins to cell surface
T cells constantly inspect surface of cells

Question 6

Where are self proteins expressed? Which cells are they on?

Answer 6

Expressed on cell surface, within groove of MHC

All nucleated cells

Question 7

Do circulating T-cells respond to self peptides on MHC-1?

Answer 7

No - only respond if abnormal peptide expressed on surface

Question 8

What is meant by the MHC or genetic restriction of the immune response?

Answer 8

T-cells can only respond to antigens if they are presented in MHC molecule

Question 9

What cell receptors bind to MHC?

Answer 9

T cell receptors
B cell receptors
(CD4 and CD8 can also bind)

Question 10

Which cells are antigen presenting cells (APCs)?

Answer 10

Dendritic cells
Macrophages
B-cells
Basophils

Question 11

Immunity can be naive or primed. Where do these different immune statuses start their response?

Answer 11

Naive - lymph nodes, at draining site of antigen exposure

Primed - local site of antigen exposure

Question 12

What lymphoid tissues are involved with naive or primed immune response?

Answer 12

Naive - lymph nodes and spleen

Primed - MALT

Question 13

How does naive or primed status affect immune response time?

Answer 13

Naive - slow >3 days

Prime - fast 1-2 days

Question 14

What are the 2 routes of antigen entry into cells? Are these MHC class I or II restricted? (route of entry dictates what type of antigen processing and presentation)

Answer 14

Phagocytosis/endocytosis - MHC class II restricted
Direct entry to cytosol - MHC class I restricted

Question 15

What are the 2 types of antigen processing? What causes these?

Answer 15

Endogenous - caused by antigen entering cell via phagocytosis/endocytosis
Exogenous - caused by antigen directly entering into cytosol

Question 16

Exogenous antigen processing involves the MHC class II pathway. Which cell recognises the antigens? What do they cause to be secreted?

Answer 16

CD4+ T helper lymphocytes (T cell receptor on this)

Cytokines

Question 17

Endogenous antigen processing involves MHC class I pathway. Which cell recognises the antigens? What do they cause to be secreted?

Answer 17

CD8+ T cytotoxic lymphocytes

Cytokines

Question 18

Antigen processing can be endogenous or exogenous. What type of pathogens does each respond to?

Answer 18

Endogenous - intracellular pathogens e.g. viruses

Exogenous - extracellular pathogens e.g. bacteria

Question 19

Where do B cells mature? Where do T cells mature?

Answer 19

B - bone marrow or bursa of fabricus (birds)

T- thymus

Question 20

What cell produces plasma cells?

Answer 20

B cells

Question 21

What cell produces CD4+ and CD8+?

Answer 21

T cells

Question 22

What are the 2 kinds of infections according to the immune system? What lymphocytes function in each?

Answer 22

Intracellular infection - cytotoxic T cells

Extracellular infection - B cells, secrete antibodies

Question 23

Infections can be extracellular or intracellular. Do B cells or T cells work inside or outside of a cell?

Answer 23

B cells - outside a cell, produce antibodies to bind to pathogen
Cytotoxic T cells - inside a cell

Question 24

Why can’t antibodies function during intracellular infections?

Answer 24

Antibodies cannot penetrate cell membrane

Question 25

What causes clonal expansion?

Answer 25

Antigenic stimulation

Co-stimulation (activation of B or T cell stimulates proliferation)

Question 26

What happens during clonal expansion? What cell does this happen to? What is this cell called after clonal expansion?

Answer 26

Lymphocyte cell enlarges
Stops migrating
mRNA and protein synthesis
Now called lymphoblasts- these divide