Question about GVHD and MHC Class II

[JasonE]

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Not sure where to ask this. But

Kaplan keeps saying that people with bare lymphocyte syndrome (no MHC Class 2 expression, so no CD4 cells because no positive selection for them) cannot suffer from GVHD.

Can anyone explain why?

 

[septoplasty]

Yea, because those are the ones that recognize host cells as foreign.

So therefore, people with low CD4 count wont have a graft rejection, and also if you're transferring BM for example, the CD4 cells from the graft will recognize host cells as foreign (different MHC), so therefore will attack the host.

 

[JasonE]

Yea, because those are the ones that recognize host cells as foreign.

So therefore, people with low CD4 count wont have a graft rejection, and also if you're transferring BM for example, the CD4 cells from the graft will recognize host cells as foreign (different MHC), so therefore will attack the host.

maybe i'm missing the point, but how are CD4 cells the ones that recognize the host cells as foreign? In GVHD, isn't it the cd8 t-cells in the graft (bone-marrow) recognizing the MHC molecules of the host as foreign? what does host cd4 cells have to do with it?

 

[septoplasty]

maybe i'm missing the point, but how are CD4 cells the ones that recognize the host cells as foreign? In GVHD, isn't it the cd8 t-cells in the graft (bone-marrow) recognizing the MHC molecules of the host as foreign? what does host cd4 cells have to do with it?

Yes, sorry, its CD8 cells (kills turmor cells, viral infected cells).

Normally, before doing a BM transplant, they undergo irradiation so these cells are destroyed!

🙂

 

[JasonE]

so then what does host cd4 have to do with the process? so confused. can't find any sources that explain this

 

[Step1Hash]

so then what does host cd4 have to do with the process? so confused. can't find any sources that explain this

I think Kaplan is either wrong or they meant to say that if the donor has Bare Lymphocyte Syndrome then there wont be GVHD. Is it possible that you misinterpreted what they had said? Otherwise, I am just as confused as you are.

 

[peace1]

bare lymphocyte syndrome is MHC class II deficiency, therefore, these patients are deficient in CD4+ cells because of failure of positive selection in the thymus.

MHC class I is expressed normally so they do have CD8+ cells, but their function is diminished by abscence of TH1 cell cytokines. Because as you remember, IL-12 makes IL-2, IFN-gamma and activate macrophages & CD8+ T cells....(FA 2010 pg. 200)

So low CD8+ T cells---> no GVHD.

This is just my opinion... please correct me if i am wrong...

 

[JasonE]

bare lymphocyte syndrome is MHC class II deficiency, therefore, these patients are deficient in CD4+ cells because of failure of positive selection in the thymus.

MHC class I is expressed normally so they do have CD8+ cells, but their function is diminished by abscence of TH1 cell cytokines. Because as you remember, IL-12 makes IL-2, IFN-gamma and activate macrophages & CD8+ T cells....(FA 2010 pg. 200)

So low CD8+ T cells---> no GVHD.

This is just my opinion... please correct me if i am wrong...

all true, but in GVHD isnt it the donor CD8 thats attcking this host (recipient)? unless the donor cd8 needs host cd4 for activation. Kaplan even has a question on this in their miniQbank, but its not explained. they clearly say a host lacking cd4 doesnt have to worry about GVHD if he is receiving a transplant.

 

[peace1]

all true, but in GVHD isnt it the donor CD8 thats attcking this host (recipient)? unless the donor cd8 needs host cd4 for activation. Kaplan even has a question on this in their miniQbank, but its not explained. they clearly say a host lacking cd4 doesnt have to worry about GVHD if he is receiving a transplant.

Yes I agree with you.
If Bare Lymphocyte Syndrome is present in the DONOR(not recipient) there will be no GVHD because they all will be deficient in t cells...