Haemopoeitic progenitor
cell transplantation
Haemopoetic progenitor cell transplantation is used in an attempt to
cure various haematological and immunological conditions. Treatment begins with
ablation of the existing diseased marrow using cytotoxic drugs and/or total
body irradiation. This induces pancytope nia and severe immunodeficiency
risking bacterial infection, bleeding and anaemia. Total body irradiation has a
number of potential late complications including thyroid underactivity, gonad
underactivity, cataract formation, diarrhoea, sun burn and nausea.
During this pancytopaenic period support includes the following:
·
Blood transfusion, if haemoglobin
falls below 10.0 g/dL, (CMV negative if patient and donor have not had CMV).
Blood is irradiated to prevent graft versus host disease.
·
Platelet transfusions may be
used.
·
Patients are maintained in a filtered
air environment. Prophylactic antibiotics and antivirals can be used. The
pancytopaenia is reversed by haemopoetic progenitor cell transplantation
(infusion into a peripheral vein of haemopoetic progenitors, which finds its
own way to the marrow cavity and regenerates it). Grafts may be allografts (HLA
matched sibling or unrelated donors) or autologous (from self) either bone
marrow or more recently peripheral blood stem cell transplants and cord blood.
Allografts risk the negative effect of graft versus host disease (GVHD)
where mature T cells in the transplant recognise the rest of the body as
‘nonself ’ and therefore attempt to reject it. Coupled to this is a positive
phenomenon known as the graft versus leukaemia effect (GVL) where the donor
marrow recognises any remaining leukaemic cells and mounts an immunological
attack. Acute GVHD may occur within the first 3 months and subsequently chronic
GVHD may develop. Acute GVHD affects HLA-rich tissue with desquamation of the
skin, impairment of liver function and diarrhoea. Lymphocyte-depleted marrow
reduces the risk of GVHD, but also eliminates the graft versus leukaemia effect
and may thus increases the risk of relapse.
Chronic GVHD, which occurs after 3 months may be an extension of acute
GVHD or may occur in patients who never showed clinical evidence of acute GVHD.
·
Ocular manifestations:
Irritation, photophobia, and SICCA syndrome.
·
Gastrointestinal system:
Abdominal pain dysphagia, odynophagia, weight loss, malabsorption and liver
disease.
·
Respiratory system: Obstructive
lung disease usually nonresponsive to bronchodilator therapy.
·
Neuromuscular system: Weakness,
neuropathic pain, muscle cramps.
Autografts (frozen haemopoetic progenitors from the patient) is not
associated with GVHD or GVL and may involve reinfusion of leukaemic cells.
However, they have the advantage of availability. Peripheral stem cell
transplants are now used more frequently than autologous bone marrow
transplantation. They have the advantage that more progenitor cells are collected
and thus rescue from pancytopenia occurs more rapidly.
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