Monitoring Engraftment

Question 1

Patients undergoing transplant usually receive a myeloablative regimen - why?

Answer 1

Designed to deplete malignant cells within the bone marrow, peripheral blood and lymph nodes

Question 2

Provide some details on donor lymphocyte infusions

Answer 2

• combat recurrence of the disease

- Donor T cells administered to patient post transplant if disease returns

Question 3

What is chimerism?

Answer 3

• presence of donor cells within the host

- 100% chimerism means no recipient cells can be detected within the compartment under investigation (e.g. Bone marrow)

Question 4

Initially developed for the field of forensic science, what does the technique of DNA profiling involve?

Answer 4

• Microsatellite regions of DNA within genome incorporate short tandem rpts of DNA sequences, the number of which vary between individuals and can be used as a means of genetic identification
• Two alleles amplified for each loci. fragments generated are identified by size/fluorescent tag

Question 5

How is discrimination increased in genetic profiling?

Answer 5

• Increasing number of STR regions amplified
• Amplifying just one gives low discrimination as chances of another individual sharing same number of repeats is around 1 in 20

Question 6

How is genetic profiling applied in post transplant assessment of donor engraftment?

Answer 6

• genetic profiling of donor and recipient pre-transplant samples to identify informative alleles
• single marker then used to measure post-transplant engraftment OR the multiplex can be run (mean derived from multiple values)

Question 7

How is the percentage donor chimerism worked out through genetic profiling analysis?

Answer 7

• Peak height/area expressed as arbitrary values and can be used to calculate amount of PCR product
• % donor chimerism = ((donor allele 1 + donor allele 2)/(donor allele 1 + donor allele 2 + recipient allele 1 + recipient allele 2))*100

Question 8

What are the various types of transplant?

Answer 8

• Sibling allogeneic
• Haplo-allogeneic
• Matched unrelated donor
• Autologous
• Syngeneic
• Umbilical cord

Question 9

What is a sibling allogeneic donor transplant?

Answer 9

Donated cells from a sibling

Question 10

What is a haplo-allogeneic donor transplant?

Answer 10

Donated cells from a parent or child who shares half of their inherited alleles with the recipient

Question 11

What is a matched unrelated donor transplant?

Answer 11

Donated cells from an unrelated donor (usually from bone marrow register)

Question 12

What is an autologous transplant?

Answer 12

Uses the patients own cells - harvested when they were in remission

Question 13

What is a syngeneic donor transplant?

Answer 13

• Donated cells from an identical twin

- Due to the genetic identity between the identical twins this type of transplant is similar in effect to the autologous

Question 14

What are the advantages of umbilical cord/double cord transplants?

Answer 14

• Uses progenitor cells so they are naive and have very little immunogenicity
• Means they do not have to be as closely genetically matched to the recipient and would therefore be available to larger number
• Two cord harvests increases number of cells infused into patient

Question 15

What are the disadvantages of umbilical cord/double cord transplants?

Answer 15

• Small number of progenitors available within a cord sample
• Without strong immunological presence, cord donation is less able to fight the leukaemia cells should they return
• Presence of three DNA profiles following double cord transplant greatly reduces potential of identifying multiple informative alleles for chimerism analysis