Physiology: immunodiagnosis and immunotherapy

Question 1

ELISA (enzyme linked immunosorbent assay)
- Describe the setup

Answer 1

Question 2

Difference between polyclonal antibodies and monoclonal antibodies?

Answer 2

Polyclonal:
- Obtained by immunising animals against a specific antigen, and extracting the antibodies
- Antibodies may be for different epitopes and/or have different isotypes (thus affinities)

Monoclonal:
- Genetically engineered
- Can isolate high affinity (ie. one isotype) antibodies

Question 3

IMMUNOHISTOCHEMISTRY
What is it?

Answer 3

Where the secondary enzyme is linked to an enzyme (eg. peroxidase or alkaline phosphatase) which can produce a coloured product

Question 4

IMMUNOFLUORESCENCE
What is it?

Answer 4

Antibodies can be labelled with flurochromes, and be used to detect interactions by fluorescent microscopy

Question 5

FLOW CYTOMETRY
What is it?

Answer 5

Specific cell surface markers (eg. CD4, CD8) are labelled with mAbs conjugated to different fluorescent markers

Question 6

MONOCLONAL ANTIBODIES
Naming?

Answer 6

Question 7

MONOCLONAL ANTIBODIES
Two main mechanisms?

Answer 7

• Bind to cell surface molecules of target cells, leading to depletion of target cells
• Bind to and modulate function of target molecule (eg. anti-TFNa antibodies for RA)

Question 8

CAR-T cells
Describe their structure

Answer 8

Question 9

CAR T cells
- Is neurotoxicity a problem? Expression of what protein may explain this?
- Impact on cytokines? Treating this?
- 2 reasons why CAR T cells might not work for solid tumours (only blood cancers)?
- High cost?

Answer 9

Yes - CD19
May cause cytokine storm - treat with mAbs against pro inflammatory cytokiens
Might not be able to penetrate solid tumours, may not be able to overcome suppressive tumour microenvironment
Yes - $500,000 per patient

Question 10

What are the 3 signals required for T cell activation?

Answer 10

Question 11

CHECKPOINT INHIBITORS
What do they do?
Are checkpoint inhibitors good or bad in
- Self cells
- Cancer cells

Answer 11

Downregulates auto reactive T cells - thereby preventing autoimmunity

Good in self cells (don’t kill healthy self cells) but bad in cancer cells (don’t kill bad cancer cells).

Question 12

CHECKPOINT INHIBITORS
Functions of CTLA-4 and PD-1 as checkpoint inhibitors?

Answer 12

Question 13

CHECKPOINT INHIBITORS
In cancer cells, checkpoint inhibitors can prevent killing.
How can this fact be exploited to treat cancer?

Answer 13

Make mAbs to block checkpoint inhibitors on cancer cells - promoting cancer cell destruction

Question 14

CHECKPOINT INHIBITORS
Ipilimumab (CTLA-4 inhibitor)
- effect on survival for stage 4 melanoma?

Nivolumab (PD-1 inhibitor)
- What was the main driver of the response to the medication?

Best results were obtained from which treatment?

Answer 14

Modest improvements in survival (compared to vaccine)
PD-L1 expression - antibodies only worked against PD-L1 when the tumour cells had PD-L1
Combined treatment of both drugs