Leukaemia And Lymphoma Flashcards
Where are B cells produced?
In the bone marrow
What happens once B cells have been produced?
Selected into the peripheral blood
Travel to secondary lymphoid organs eg lymph nodes and spleen
Recruited into germinal centres if there is an antigen present
What is in the cortex of lymph nodes?
B and T cells
What is in the medulla of lymph nodes?
Plasma cells
Macrophages
B cells
Sinuses which lymph can flow into
What are the different types of lymphocytes?
B and T cells
Natural killer cells
What happens if there is an antigen in a lymph node?
B cells are recruited to the germinal centre (follicles found in the cortex)
B cells evolve and produce high affinity antibodies to resist infections
What happens in somatic hypermutation?
When deaminase enzymes introduce point mutations onto the variable region of DNA that codes for the antibody
Introduces uracil to the DNA
Uracil then excised and swapped for a different base
How do mutations accumulate in somatic hypermutation?
Uracil base swapped in then replaced
B cells proliferate and mutations accumulate so that there are many different receptors with different affinities for the antigen
After proliferation of B cells, how are they selected and what happens to them?
The B cell with the highest affinity is selected and differentiates into plasma cells to produce antibodies
What is class switching antibodies and why does it happen on B cells?
IgM switches to IgG
The on is changes, variable region stays the same so affinity stays the same
Allows the antibody to interact with different effector molecules
Requires deaminase again
Why are lymph nodes a ‘perfect storm’ for cancer?
Have intense proliferation of B cells with many mutations being produced
What type of lymphoma is Burkitt’s?
A non-Hodgkin’s lymphoma
What forms of burkitt’s can you get and what is the geographical distribution?
Sporadic happen in the west
Epidemic more common in Africa
What is Burkitt’s lymphoma associated with?
EBV
Malaria
What is the mutation in Burkitt’s lymphoma?
The translocation of the MYC gene from chromosome 8 to 14, causing it to be expressed
Why can the MYC gene easily by translocated in Burkitt’s lymphoma?
Found close to constant regions
Enhancer elements normally drive transcription of these genes (antibody genes), can also drive MYC genes, causing it to be expressed
What does the MYC gene code for?
A transcription factor which causes proliferation of the cell
How can the translocation in Burkitt’s lymphoma be detected?
Fluorescence in situ hybridisation
What is FISH?
Labelled single-stranded DNA can interact with sufficiently similar complementary sequences to form complexes/hybrids
This allows specific sequences/genes to be detected
Who is follicular lymphoma typically seen in?
Older people
How do people with follicular lymphoma typically present?
Lymphadenopathy
Weight loss
Night sweats