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let us look at tumors of the immune
system leukemia develops in the bone
marrow there are a number of different
types of leukemia the main ones are
acute lymphoblastic leukemia acute
myeloid leukemia chronic lymphocytic
leukemia and chronic myeloid leukemia
there are subtypes of each of these
types of leukemia lymphomas in contrast
develop in the lymphatic system the two
main lymphomas are Hodgkin lymphoma and
non-hodgkin lymphoma myelomas are tumors
of plasma cells here we have a stem cell
that is giving rise to pre B lymphocytes
acute lymphoblastic leukemia is usually
derived from immature pre b-cells blasts
are present in the bone marrow and blood
in chronic lymphocytic leukemia and
lymphoma the malignant population is
mature B cells in CLL malignant cells
are present in the blood in lymphoma the
malignant cells are present in the lymph
node and sometimes in other tissues
plasma cells give rise to myeloma in
myeloma the clone of malignant plasma
cells produces a monoclonal
immunoglobulin in other words all the
antibody is absolutely identical because
it's derived from a malignant clone of
plasma cell t-cell malignancies are
somewhat less common T cells are not
infected by epstein-barr virus which is
a major way in which b-cells
can become malignant also T cells are
somewhat more susceptible to apoptosis
and therefore less able to survive there
are also myeloid leukemias derived from
my
Oh Genesis as well as these lymphoid
leukemias that you can see on this slide
chronic lymphocytic leukemia is rather
unusual in that leukemic cells have on
their cell surface a molecule that is
normally present on B cells but also a
molecule that is normally present on T
cells as you can see in this flow
cytometry diagram there are normally
cd19 positive B cells and then
separately cd5 positive B cells however
in chronic lymphocytic leukemia the
cells expressed both of those molecules
on their surface in other words a
molecule that is characteristic of B
cells but also a molecule that is more
normally characteristic of T cells
post-transplant
lymphoma can arise due to EBV infection
in individuals that are receiving
immunosuppression in order that they do
not reject a transplanted tissue or
organ prior to a renal transplant this
woman had memory T cells responding to
Epstein Barr virus the Epstein Barr
virus infection was controlled by the T
cells however following a transplant the
immunosuppressive drug cyclosporine has
made the memory cells non-responsive and
there is a polyclonal increase in EBV
infected b-cells there becomes a
situation in which there is uncontrolled
EBV infection which drives B cell
proliferation
the polyclonal B cell proliferation will
improve if the cyclosporine is stopped
however with ongoing clif eration Mik
translocation can occur within the B
cells there is a malignant
transformation resulting from this Mik
translocation and the development of
lymphoma the polyclonal growth of
b-cells has increased the
for this translocation to occur the
monoclonal B cell proliferation will
continue after cyclosporine is stopped
and the patient develops the symptoms of
lymphoma in multiple myeloma
there are plasma cells in the bone
marrow that become malignant and
therefore a clone of rapidly replicating
plasma cells pumping out huge amounts of
antibody of a single specificity
development they produce what is
referred to as a power protein and this
can be detected on an electro phoretic
gel we can see the power protein band in
the gamma region from the patient on
this gel in contrast in a healthy
individual that monoclonal band is
missing because their antibodies are
totally polyclonal of a huge mixture of
different specificities
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you