Transplantation Flashcards
autologous transplant
the transplant tissue is from the same individual e.g. skin graft
syngeneic transplant
between twins
allogenic transplant
between genetically non-identical members of the same species
xenogenic transplant
between different species
cadaveric transplant
organs from dead donor
what is rejection
when the immune system attacks the transplant
what can reduce the risk of rejection
donor and recipient must be AOB compatible close as possible HLA match recipient must not have anti-donor HLA antibodies immunosuppression
what is hyperacute rejection
immune system rejects organ/translant within hours
pathophysiology of hyperacute rejection
antibodies bind to ABO blood group or HLA class I antigens on the graft type II hypersensitivity reaction is triggered IgG and IgM bind and recruit macrophages and complement system causing cell damage
acute rejection
delayed type IV hypersensitivity reaction days-weeksusually due to HLA incompatibility
pathophysiology of acute rejection
dendritic cells from donor stimulate an allogenic response in lymph node node releases T cells which target donor organ
afferent phase of acute rejection
donor MHC molecules on dendritic cells recognised by patients CD4+ T cells
efferent phase of acute rejection
T cell recruit macrophages< NK cells, B cellsgraft is targeted
what is chronic rejection
takes place over months/years often mediated by T cells can be caused by pre-existing autoimmune disease
role of immunosuppresants in transplants
prevent rejection at the time of the transplant if the drugs are stopped rejection will occur
role of corticosteroids in transplants
low dose prevent early stages of rejection target antigen presenting cells at a high dose they can treat rejection
how does ciclosporin work
immunosuppressant interacts with proteins in T cell signalling cascade
examples of monoclonal antibodies
basiliximab daclizumab
role of monoclonal antibodies in transplants
used in acute graft rejection
rapamycin mechanism of action
inhibits signals from IL-2 receptor
role of rapamycin in transplants
prevents acute graft rejection
side effects of rapamycin
raises lipid and cholesterol levels anaemia hypertension rash thrombocytopenia
what are anti-proliferatives
drugs that inhibit DNA production
anti-proliferatives examples
azathioprine mycophenolate mofetil methotrexate
stem cell sources for transplant
bone marrow peripheral bloodcord blood
when is stem cell transplantation used
last resort for haematological malignancies primary immunodeficiency severe combined immunodeficiency
autologus stem cell therapy
marrow is removed frozen and reinfused after chemotherapy has been given
allogenic stem cell therapy
higher risk risk of graft vs host disease
what is conditioning for SCT
high dose chemo/radiotherapy to destroy stem cells before new ones are given
what is graft vs host disease
multi-system complication of allogenic bone marrow transplantationT cells respond to allogenic recipient antigens
what is the billingham criteria
criteria used to diagnose graft vs host disease
three requirements to meet the billingham criteria
transplanted tissue has immunologically functioning cells recipient and donor are immunologically differenr recipient is immunocompromised
when does acute graft vs host disease happen
within 100 days
features of acute graft vs host disease
affects skin, liver, GImaculopapular rashjaundicewatery/bloody diarrhoea nausea vomiting fever
features of chronic graft vs host disease
any organ system can be involved scleroderma vitiligo corneal ulcers scleriti dysphagia oral ulcers oral lichenous changes obtructive or restrictive lung disease
what drugs would you use in graft vs host disease
immunosuppressants
how can hyperacute rejection be triggered in xenotransplantation
humans make antibodies against sugar side chains that they are exposed to in the gut the antibodies can target the organ and activate the complement system
