7. Adaptive Immunity

Question 1

Name 4 types of antigen-presenting cells and where they are found

Answer 1

Dendritic cells - lymph nodes
Langerhans’ cells - skin
Macrophages - most tissues
B cells - lymphoid tissue

Question 2

What is macropinocytosis?

Answer 2

Engulfing of soluble particles, such as by antigen presenting cells

Question 3

What type of immunity is activated by antigen presenting cells when they capture, process and present extracellular microbes? What does this involve?

Answer 3

Humoral immunity - B lymphocytes antibodies, complement, phagocytosis

Question 4

What type of immunity is activated by antigen presenting cells when they capture, process and present intracellular microbes? What does this involve?

Answer 4

Cell-dependent immunity - cytotoxic T lymphocytes, antibodies, macrophages

Question 5

What is the major histocompatibility complex (MHC)? What else can it be called?

Answer 5

Complex antigen presentation occurs by

HLA

Question 6

What is the main function of MHC class I? Where are the class I molecules found?

Answer 6

Present peptides from intracellular microbes

All nucleated cells

Question 7

What is the main function of MHC class II? Where are the class II molecules found?

Answer 7

Present peptides from extracellular microbes

Dendritic cell, macrophages, B cells

Question 8

How does the genetics of MHC class I and II ensure that there is an increased number of different MHC molecules in an individual and also increased presentation of different antigens/microbes?

Answer 8

Co-dominant expression

Polymorphic genes

Question 9

What are the two main structural features of MHC class I and II molecules?

Answer 9

Peptide binding cleft with highly polymorphic residues

Broad specificity

Question 10

What type of T cells are MHC class I recognised by?

Answer 10

CD8+

Question 11

What class of T cells are MHC class II recognised by?

Answer 11

CD4+

Question 12

What MHC class does the endogenous pathway present antigens on? Which cells does this occur on?

Answer 12

MHC class I
All cells with a nucleus

Question 13

What MHC class does the exogenous pathway present antigens on? Which cells does this occur on?

Answer 13

MHC class II
Antigen presenting cells

Question 14

Which class of MHC molecules are HLA-A, HLA-B and HLA-C?

Answer 14

Class I

Question 15

In both antigen presenting pathways what peptides are presented?

Answer 15

Both self and non-self

Question 16

What does susceptibility to infections depend on?

Answer 16

Types of MHC molecule - if you have the right one to present the microbe

Question 17

What can patients who are elite controllers or long-term nonprogressors do?

Answer 17

Control viral replication (high T cell count and low viral load)

Question 18

What makes a HIV-infected individual a slow progress or?

Answer 18

HLA typing leads to
MHC molecules presenting key peptides for the survival of the virus (unmutated)
So effective T cell response

Question 19

What makes a HIV-infected individual a rapid progressor?

Answer 19

Homozygote in HLA-1 alleles
MHC molecules presently mutated peptides (less critical for survival of virus)
Poor recognition by T cells, so poor T cell responses

Question 20

What is the major cause for organ transplant rejection?

Answer 20

HLA molecules not a close enough match between donor and recipient. Can lead to graft-versus-host reaction

Question 21

Name two autoimmune diseases that HLA molecules are thought to be associated with

Answer 21

Ankylosing spondylitis

Insulin-dependent diabetes mellitus

Question 22

What is needed other than just the right receptors for the correct MHC and antigen, on a naive T cell for the activation of the cell?

Answer 22

Costimulatory signals

Question 23

What class of MHC and therefore T cells activate cytotoxic T cells?

Answer 23

MHC class I and therefore CD8+ in the endogenous pathway (NB MHC class II will also be present) for intracellular microbes

Question 24

What does the activation of cytotoxic T lymphocytes result in?

Answer 24

Infected cell death

Question 25

What is needed either than just recognition by a cytotoxic T lymphocyte of the MHC class I and antibody on the infected target cell to cause its death?

Answer 25

Perforins granzymes

Question 26

What is the main antibody regulating allergies? What other functions does it have?

Answer 26

IgE

Immunity against helminths, mast cell degranulation

Question 27

What is the role of IgM? Therefore is it higher or lower than IgG in the primary response to an infection?

Answer 27

Complement activation

Higher (NB will be the same amount produced in the secondary response)

Question 28

What is the role of IgG? Therefore is it higher or lower than IgM in the secondary response to an antigen?

Answer 28

Enhances phagocytosis via opsinisation, activated complement, provides neonatal immunity, neutralises toxins/viruses
Higher

Question 29

Which MHC class activates B cells, isotype switching and then antibody production?

Answer 29

MHC class II (CD4+ naive T cells)

Question 30

What is the immune function of IgA?

Answer 30

Mucosal immunity

Question 31

Give two medical achievements derived from the study of the adaptive immune response

Answer 31

Disease prevention - vaccination

Immunoglobulin therapies - immune deficiencies