angel23
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A 45 yr old male recieves a liver transplant.One week later,he develops desquamating rash and bloody diarrhoea.imaging reveals multiple ulcerations in intestinal mucosa.wat is the cause..??
1..Host T cell senstization against graft MHC or
2.Graft T cell sensitization against host MHC
plz explain
thanks
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| pr20
Forum Senior
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2.Graft T cell sensitization against host MHC
Jaundice,maculopapular skin rash,diarrhea,and hepatosplenomegaly after organ transplantation(bone marrow,liver and blood transfusions) indicate the graft versus host (GVH)reaction.
GVH occurs in cases where competent donor T-lymphocytes are transplanted in to a patient who does not posses functional immune system.T cells from the transplant recognize the host MHC molecules as nonself and attack the host.This is a type 4 hypersensitivity reaction.
Donor lymphocytes produce IL-2---->activate NK cells---->activated NK cells are called as lymphokine-activated NK cells(LAK's).LAK cells are the primary effector cells in acute GVH reaction.
GVH reaction may be prevented by the following ways:
1.Tcell depletion by irradiating the transfused products
2.Antibody prophylaxis with IV immunoglobulins or cyclosporine, combined with short course of methotrexate.
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| angel23
Forum Guru
Topics: 34
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thanks pr20....got tht
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| angel23
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Topics: 34
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another ques...
a 34 yr old man with kidney transplant experiences low grade fever and decreased urine output after one week of transplantation.Graft biopsy demonstrates diffuse infilteration of mononuclear cells....wat is the cause of this....
1.host T cell response to graft MHC...or
2.graft Tcell response to host MHC
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| angel23
Forum Guru
Topics: 34
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both the questions are 4rm UW....cant get the answer right...
in first it was 2. n in second one it was 1.
dint get this
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| pr20
Forum Senior
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While the first one is graft versus host reaction,the second one(with kidney transplant)is host versus graft reaction which can be divided in to 1.hyperacute 2.acute and 3.chronic types
The problem with host versus graft reaction is that if donor and recipient MHC molecules are not identical,the recipient T-cells will recognize the donor MHC molecules as nonself and trigger both helper and cytotoxic T-cell response against the transplanted tissue.
It is very important to remember that hyperacute host versus graft reaction is antibody mediated(type 2 hypersensitivity reaction) while acute and chronic host versus graft reactions are lymphocyte mediated(type 4 hypersensitivity reactions).
Hope iam clear.
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| angel23
Forum Guru
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thanks again...its clear to me now
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| pr20
Forum Senior
Topics: 18
Posts: 161
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Graft versus host reaction(graft T cell sensitization against host MHC):-
presents with classic symptoms of jaundice,maculopapular skin rash,diarrhea,and hepatosplenomegaly after organ transplantation.
Host versus graft reaction(host T cell response to graft MHC):-
presents with low grade fever and decreased urine output,graft biopsy is important in identifying types.
Hyperacute reaction(occurs within minutes to few hours)-vascular fibrinoid necrosis and neutrophil infiltration within arterioles,glomeruli,and peritubular capillaries.
Acute reaction(occurs from days to few weeks)-a dense interstitial cellular infiltrate which is predominantly mononuclear,consisting of CD8+ and CD4+ lymphocytes.
Chronic reaction(occurs from many weeks,months to years)-obliterative intimal smooth muscle hypertrophy and fibrosis.
Graft versus host reaction,acute host versus graft reaction,and chronic host versus graft reactions are lymphocyte mediated(type 4 hypersensistivity reactions) while only the hyperacute host versus graft reaction is preformed antibodies mediated(type 2 hypersensitivity reaction).
Hope you understood the differences.
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| macintosh
Forum Elite
Topics: 38
Posts: 178
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May I ask, if there is a difference between accelerated graft rejection and acute rejection?
According to the definition in Medilexicon medical dictionary (http://www.medilexicon.com/medicaldictionary.php?...), accelerated rejection is a transplant rejection that manifests in less than 3 days. If so, is accelerated rejection related to acute rejection? Please also mention its mechanism.
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