Immunology

Question 1

What are some substances secreted by skin and mucous membranes that act as a barrier to pathogens?

Answer 1

1. Mucins
2. Protease inhibitors
3. Peroxidase
4. Antimicrobial peptides
5. Acid pH (3-5)
6. Lysozymes
7. Histatins

Question 2

Which cytokines are released by phagocytise cells?

Answer 2

IL-1, IL-6, IL-8, TNF

Question 3

What are 11 key conserved molecular patterns?

Answer 3

1. Lipopolysaccharides (on gram -ve bacteria cell wall)
2. Bacterial lipoproteins and lipopeptides
3. Lipoteichoic acids (on gram +ve bacteria cell wall)
4. Porins (on gram -ve bacteria cell wall)
5. Peptidoglycans
6. Mannose-rich glycans Flagellin protein
7. N-formylmethionine
8. Zymosan
9. Bacterial and viral nucleic acid
10. Double stranded viral RNA
11. Single stranded viral RNA

Question 4

What are the four receptor types (pattern recognition receptors) that recognise and bind pathogen associated-molecular patterns (PAMPs)?

Answer 4

1. Cell surface (facilitate uptake of pathogens into cells or act as signals for cell movement or destruction)
2. Toll-like receptors (activate intracellular signalling pathways)
3. Endosomal toll-like receptors (includes TLR-3, 7, 8, 9)
4. Cytosolic
   a. RIG-like receptors
   b. NOD-like receptors

Question 5

What are natural killer cells?

Answer 5

Cells involved in the non-specific cytotoxic killing of virus-infected, damaged or cancerous cells.

Question 6

How are NK cells able to recognise and kill target cells?

Answer 6

1. Balance between activating and inhibiting signals (decreased MHC expression on a cell leads to decreased inhibitory signal)
2. Ab-dependent cellular cytotoxicity mechanisms (they induce apoptosis via perforin and granzyme release)

Question 7

Where are IgA antibodies found? How do they work?

Answer 7

External secretions and blood

They attach to and inactivate foreign pathogens (block key attachment proteins)

Question 8

Where are IgE antibodies found? What do they do?

Answer 8

Blood

Attach to mast cells and basophils (lead to release of vasoactive amine, cytokines and enzymes)

Question 9

What are IgM antibodies and what do they do?

Answer 9

They fix complement and cause death of cells

Produced early during immune response

Pentametric—> agglutination

Question 10

What is the predominant antibody in serum?

Answer 10

IgG

Some fix complement, others cross placenta, others bind to cells via Fc receptors

Question 11

What antibodies are found in colostrum?

Answer 11

M, G and A

Question 12

What characterises secondary immune responses?

Answer 12

Faster
More antibodies
Different antibodies
Higher affinity
T cell help

Question 13

CD8 cells recognise what class of MHC?

Answer 13

MHC class I

Question 14

Describe the composition of the MHC class I molecule?

Answer 14

Has an alpha chain and a B2-microglobulin.

Alpha is variable and forms the BBQ and sausages to capture

B2-microglobulin is constant among individuals and does not interact with individual

Question 15

On which cells are MHC II molecules expressed?

How do their chains differ to MHC I molecules?

Answer 15

Antigen presenting cells (macrophages, dendritic cells, B cells).

Alpha and beta chain are both variable and they both form the BBQ 🍖

Question 16

What is a MHC haplotype?

Answer 16

The combination of MHC genes present on a particular chromosome.

Question 17

An individual can have 6 MHC class I molecules on their cells surface. This is because they get 3 alpha chain alleles each from their mum and dad. Why is there higher diversity with the number of MHC class II molecules if they get 4 each?

Answer 17

Because each alpha chain can associate with several beta chains

Question 18

What is clonal selection theory and what are some reasons why is it wrong?

Answer 18

The theory that antigens select the antibody to be made by each T cell. This is wrong because:

There is a need for different isotopes without changing antigen specificity.
The theory requires Abs to be soluble and membrane bound.
B cells need to become memory cells

Question 19

What are the two light chain variants of an immunoglobulin?

Answer 19

Lambda and kappa (variable, joining and constant domains)

Question 20

Upon activation, B cells differentiate into…?

Answer 20

Blast cells which then become IgM-producing plasma cells

Question 21

How are soluble antibodies made?

Answer 21

Replacement of the last 40 or so mostly hydrophobic amino acids by 20 hydrophilic amino acids

Question 22

How does class switching occur?

Answer 22

RNA splicing (DNA looping and recombination)

Question 23

How are monoclonal antibodies produced and why are they useful?

Answer 23

Via fusion with myeloma cells. Allows diagnostic testing for specific antigens.

Question 24

What is antigen processing?

Answer 24

The process of transforming antigens to small peptides to present to T cells in association with MHC

Question 25

What makes up the thymus?

Answer 25

I,mature T cells from the bone marrow and the thymus stroma (including thymic dendritic cells, epithelial cells and macrophages)

Question 26

What are cytokines?

Answer 26

Small soluble messenger proteins involved in the communication between cells (particularly those of the immune system).

Question 27

What is pleitrophy?

Answer 27

The ability of cytokines to act on different cell types

Question 28

What are some applications of cytokines in vet med?

Answer 28

Vaccine adjuvants
Antimicrobials
Therapeutics
Growth promoters
Diagnostics