Why you don't have GVHD in the host has T Cell deficiency? - USMLE Forums
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Old 12-24-2012
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Immunology Why you don't have GVHD in the host has T Cell deficiency?

Okay, this is killing me now. I've looked everywhere and can't seem to understand this.

So, this is what I understand till now: there is supposed to be a GVHD every time you do a Bone marrow transplant (unless the T-cells were killed/blocked in the transplant or there was chemo-suppressants were supplied to the host). This is mostly mediated by T-Cells of the donor, that recognize the host cells as foreign (an opposite to a normal transplant reaction).

And, BOTH HUMORAL AND CELLULAR IMMUNITY play a part in this i.e the T-Helper cells of the donor recognize and launch an attack on MHC Class II of the host, and the T-Cytotoxic of the donor attack the MHC Class I of the host.

So far so good. Now, from Kaplan Immuno, she says that you are not supposed to have GVHD if there is a CD4 cell deficiency in the host, and the diseases she mentioned were:

3. DiGeorge Syndrome
4. MHC Class II deficiency

I can't understand the fact why the transplant cells won't attack. They don't care if there are CD4 cells in the host or not. By the rules, the T-cytotoxic present in the transplant will attack all the Class I cells (and that means virtually all cells in the body), and the T-Helper, together will B-Cells, will take care of all the Class II cells.

Now, if she said the donor had these diseases, then it would make sense, since there will be no T-Cells to fight. But, again, that would be illogical . i.e why would you take a BM transplant from Digeorge or SCID or AIDS patient?

Anyone care to explain this. What am I getting wrong in this whole picture?

Last edited by Smashingdude; 12-24-2012 at 11:32 AM.
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Old 12-24-2012
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what i can understand from this is that in GVHD, in addition to the donor's Tcells attacking the body. the Host Tcells can also recognize the donor's tissue as self during negative selection, and begin to attack the body as if it's foreign. so in this case the prognosis would be worse. so in you said diseases AIDS,SCID,DIGEORGE e.t.c this would not happen.... but i suppose they should still be attacked by the foriegn "donor's" T-cells.

But Then again.... who cares!! you don't need to know it all... these are not how the questions are structured. and knowing this will honestly not help you answer questions.
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