Polyclonal and monoclonal Antibodies in treating leukaemia Flashcards
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?
No polyclonal antibodies may target different epitopes on the same antigen
How are polyclonal antibodies produced (6 Steps)?
- 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
How are monoclonal antibodies produced (7) ?
- 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)
Myeloma cells cannot produce what enzyme?
HGPRT
Without HGPRT cells used in overs synthesis of purines but hybrid cells are grown in HAT medium which contains Aminopterin what does this do?
Aminopterin Blocks pathway of normal purine synthesis
Without the HAT medium what would happen to the on fused myeloma cells?
The unfused myeloma cells would outgrow the hybrid cells
What does HAT medium contain?
- Hypoxanthine (purine derivative)
- Aminopterin (inhibits dihydrofolate reductase)
- Thymidine (pyrimidine)
ALL (acute lymphoblastic leukaemia) is a cancer of which type of stem cell?
Lymphoid stem cells
B-ALL is a cancer of the B-lymphoblast cells what percentage of acute lymphoblastic leukaemia is of this type?
80-85% B-ALL
T-ALL Is a cancer of theT- lymphoblast cells, what percentage of acute lymphoblastic leukaemia is of this type?
15-20% T-ALL
What are the symptoms of acute lymphoblastic leukaemia?
- 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)
How is acute lymphocytic leukaemia diagnosed?
- Aspiration biopsy
- Microscopy (bone smear)
- Blood smear
What can be seen via microscopy of the bone smear in acute lymphocytic leukaemia?
- Large numbers of lymphoblast cells
- greater than 20% = ALL
What can be seen via microscopy of a blood smear in acute lymphocytic leukaemia?
- Large numbers of lymphoblast cells
- Reduced numbers of red cells
- Reduced numbers of platelets
Name 2 antibody therapies used to treat acute lymphocytic leukaemia?
- Rituximab
- Inotuzuumab ozogamicin
What does CD stand for?
Cluster of differentiation
What to cluster of differentiation (CD) cells do?
- Used to identify immune cells
- Some act as receptors the cell signalling
Rituximab is a monoclonal antibody against which cluster of differentiation molecule?
Anti-CD20
CD20 is found on what percentage of B cells in B-ALL?
50%
What is the mechanism of action of rituximab?
- Binds to CD20 on B cells
- causes apoptosis
By which two cellular mechanisms does rituximab cause apoptosis?
- Antibody dependent cellular cytotoxicity (ADCC) - natural killer cells
- complement dependent cytotoxicity (CDC) - classical pathway
Inotuzuumab ozogamicin is a monoclonal antibody against which cluster of differentiation molecule?
CD22
CD22 is expressed in what percentage of acute lymphocytic leukaemia (ALL) patients?
> 90%
What is the function of CD22 in the B-cell?
- Inhibitory receptor which inhibits B-cell receptor signalling (BCR)
The drug Inotuzuumab ozogamicin is a monoclonal antibody which is conjugated with the cytotoxic agent, what is this agent called?
Calicheamycin
The cytotoxic agent Calicheamycin is rapidly internalised and delivered directly to the cancer cells causing apoptosis, how does Calicheamycin trigger apoptosis?
- Binds to minor groove of DNA
- Produces strand breaks in DNA
- Causes apoptosis
58% of patients achieved a complete response to Inotuzuumab ozogamicin, but survival was only modestly improved, what does this mean for treatment?
The drug Inotuzuumab ozogamicin needs to be combined with traditional chemotherapy
High doses of the drug Inotuzuumab ozogamicin can be toxic to the liver which is the best way to administer this drug?
lower dose, weekly
What are the 4 major types of leukaemia?
- Acute lymphoblastic leukaemia (ALL)
- Acute myeloid leukaemia (AML)
- Chronic lymphoblastic leukaemia (CLL)
- Chronic myeloid leukaemia (CML)
What type of cells originate from lymphoid stem cells?
- T-cells
- B-cells (plasma cells)
What cells originate from myeloid stem cells?
All non-lymphoid cells
- Eosinophils
- Basophils
- Neutrophils
- Reticulocytes (red blood cells)
- Megakaryocytes (platelets)
- Monocytes (macrophages)
When lymphocytic leukaemia is described as acute what does this mean?
There is a rapid increase in white cells
When lymphocytic leukaemia is described as chronic what does this mean?
There is a progressive buildup of white cells over time
