Polyclonal and monoclonal Antibodies in treating leukaemia

Question 1

Polyclonal antibodies are produced by different B-cells/plasma cells and they may target the same antigen but do they target they all target the same epitope?

Answer 1

No polyclonal antibodies may target different epitopes on the same antigen

Question 2

How are polyclonal antibodies produced (6 Steps)?

Answer 2

• Animal is immunised with the antigen (intraperitoneal injection)
• Animal is re-immunised
• Animal is bled
• Purification in Seraphose column
• purification continued seraphose washed to remove weak/unbound antibodies
• antibody eluted off column ready for use

Question 3

How are monoclonal antibodies produced (7) ?

Answer 3

• Animal is immunised (intraperitoneal injection)
• Antibody producing B cells removed from spleen
• Cultured with myeloma cells (in mortal)
• Myeloma cells and spleen cells fused with polyethylene glycol
• hybrid cells are immortal and can produce antibodies forever
• Clones screened (ELISA) to identify desired antibody
• Clones propagated (expanded and grown in culture medium, frozen and stored)

Question 4

Myeloma cells cannot produce what enzyme?

Answer 4

HGPRT

Question 5

Without HGPRT cells used in overs synthesis of purines but hybrid cells are grown in HAT medium which contains Aminopterin what does this do?

Answer 5

Aminopterin Blocks pathway of normal purine synthesis

Question 6

Without the HAT medium what would happen to the on fused myeloma cells?

Answer 6

The unfused myeloma cells would outgrow the hybrid cells

Question 7

What does HAT medium contain?

Answer 7

• Hypoxanthine (purine derivative)
• Aminopterin (inhibits dihydrofolate reductase)
• Thymidine (pyrimidine)

Question 8

ALL (acute lymphoblastic leukaemia) is a cancer of which type of stem cell?

Answer 8

Lymphoid stem cells

Question 9

B-ALL is a cancer of the B-lymphoblast cells what percentage of acute lymphoblastic leukaemia is of this type?

Answer 9

80-85% B-ALL

Question 10

T-ALL Is a cancer of theT- lymphoblast cells, what percentage of acute lymphoblastic leukaemia is of this type?

Answer 10

15-20% T-ALL

Question 11

What are the symptoms of acute lymphoblastic leukaemia?

Answer 11

• Anaemia (pale/tired)
• Infections (lack of appropriate white cells)
• Bleeding (insufficient platelets, bruise easily)
• Bone/joint pain space in bone marrow taken up by blast cells (No space left for red cells or platelets)

Question 12

How is acute lymphocytic leukaemia diagnosed?

Answer 12

• Aspiration biopsy
• Microscopy (bone smear)
• Blood smear

Question 13

What can be seen via microscopy of the bone smear in acute lymphocytic leukaemia?

Answer 13

• Large numbers of lymphoblast cells

- greater than 20% = ALL

Question 14

What can be seen via microscopy of a blood smear in acute lymphocytic leukaemia?

Answer 14

• Large numbers of lymphoblast cells
• Reduced numbers of red cells
• Reduced numbers of platelets

Question 15

Name 2 antibody therapies used to treat acute lymphocytic leukaemia?

Answer 15

• Rituximab

- Inotuzuumab ozogamicin

Question 16

What does CD stand for?

Answer 16

Cluster of differentiation

Question 17

What to cluster of differentiation (CD) cells do?

Answer 17

• Used to identify immune cells

- Some act as receptors the cell signalling

Question 18

Rituximab is a monoclonal antibody against which cluster of differentiation molecule?

Answer 18

Anti-CD20

Question 19

CD20 is found on what percentage of B cells in B-ALL?

Answer 19

50%

Question 20

What is the mechanism of action of rituximab?

Answer 20

• Binds to CD20 on B cells

- causes apoptosis

Question 21

By which two cellular mechanisms does rituximab cause apoptosis?

Answer 21

• • Antibody dependent cellular cytotoxicity (ADCC) - natural killer cells
• complement dependent cytotoxicity (CDC) - classical pathway

Question 22

Inotuzuumab ozogamicin is a monoclonal antibody against which cluster of differentiation molecule?

Answer 22

CD22

Question 23

CD22 is expressed in what percentage of acute lymphocytic leukaemia (ALL) patients?

Answer 23

> 90%

Question 24

What is the function of CD22 in the B-cell?

Answer 24

• Inhibitory receptor which inhibits B-cell receptor signalling (BCR)

Question 25

The drug Inotuzuumab ozogamicin is a monoclonal antibody which is conjugated with the cytotoxic agent, what is this agent called?

Answer 25

Calicheamycin

Question 26

The cytotoxic agent Calicheamycin is rapidly internalised and delivered directly to the cancer cells causing apoptosis, how does Calicheamycin trigger apoptosis?

Answer 26

• Binds to minor groove of DNA
• Produces strand breaks in DNA
• Causes apoptosis

Question 27

58% of patients achieved a complete response to Inotuzuumab ozogamicin, but survival was only modestly improved, what does this mean for treatment?

Answer 27

The drug Inotuzuumab ozogamicin needs to be combined with traditional chemotherapy

Question 28

High doses of the drug Inotuzuumab ozogamicin can be toxic to the liver which is the best way to administer this drug?

Answer 28

lower dose, weekly

Question 29

What are the 4 major types of leukaemia?

Answer 29

• Acute lymphoblastic leukaemia (ALL)
• Acute myeloid leukaemia (AML)
• Chronic lymphoblastic leukaemia (CLL)
• Chronic myeloid leukaemia (CML)

Question 30

What type of cells originate from lymphoid stem cells?

Answer 30

• T-cells

- B-cells (plasma cells)

Question 31

What cells originate from myeloid stem cells?

Answer 31

All non-lymphoid cells

• Eosinophils
• Basophils
• Neutrophils
• Reticulocytes (red blood cells)
• Megakaryocytes (platelets)
• Monocytes (macrophages)

Question 32

When lymphocytic leukaemia is described as acute what does this mean?

Answer 32

There is a rapid increase in white cells

Question 33

When lymphocytic leukaemia is described as chronic what does this mean?

Answer 33

There is a progressive buildup of white cells over time