Transplant MHC Partial Matching or Mismatching

[R_C_Hutchinson]

I've heard people talk about MHC mismatching during transplantation and I know basically nothing about it. Everyone seems to mention it in passing and how it's "sexy" and "new" but they never go into detail.

Could someone please explain?

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[agranulocytosis]

I don't understand why one would purposely MHC mismatch for a transplant. I've always thought you'd have to make sure of an MHC match (or close to it) for lower chances of rejection.

 

[Keg]

I think I remember from class that 3/6 is the bare minimum and 6/6 is obviously ideal - this on top of ABO and Rh/D. Worse match = higher rate of GvHD (but also GvMalignancy) so it may be beneficial with some tumors (i.e. leukemias) to have a partial mismatch so that the new immune system eliminates the old one. Then, I guess you could re immunosuppress the patient and do an auto with purified normal cells to restore baseline (that sounds like a lot of risk to the patient, though).

 

[osli]

We had a guest lecturer whose research was in that field come in for an optional lunch presentation. Very interesting stuff, and I don't remember one ounce of it. He went into great detail about purposeful mismatching, when you do it, when you want matches, when fetal stem cells are better and when they are worse. About the only thing I can say now about that presentation is that it is complex, and there seem to be advantages and disadvantages to all approaches and some are more suited for certain situations than others.

 

[lilnoelle]

What we were told - it can be better to have a slightly mismatched transplant (matching sibling verses identical twin) because it causes a little bit of rejection... which gets the recipient's immune system going - and you'll be less likely to have transplant cancers and myelodysplasias later on.

I don't have the lecture - and thats certainly not verbatim - but our lecturer did talk quite a lot about how it was better to have a matching sibling than a twin. My impression from him was that "mismatching" was bad, but that having a little bit of rejection is good - in fact, he reduces immune suppression on these individuals so that rejection isn't completely avoided.

 

[lilnoelle]

We had a guest lecturer whose research was in that field come in for an optional lunch presentation. Very interesting stuff, and I don't remember one ounce of it. He went into great detail about purposeful mismatching, when you do it, when you want matches, when fetal stem cells are better and when they are worse. About the only thing I can say now about that presentation is that it is complex, and there seem to be advantages and disadvantages to all approaches and some are more suited for certain situations than others.

I'm guessing we had the same lecturer.

 

[osli]

I'm guessing we had the same lecturer.

Very likely. But in our case it was a lunch presentation to a select group of students where he really just focused on his research. So we saw tons of graphs and charts, and only got a bit of insight into the basics through our questions at the end... usually something like "what is GVH?!?"

 

[lilnoelle]

Very likely. But in our case it was a lunch presentation to a select group of students where he really just focused on his research. So we saw tons of graphs and charts, and only got a bit of insight into the basics through our questions at the end... usually something like "what is GVH?!?"

haha, thats funny. Well, that would explain why you heard more about his research than we did. I thought at the time that the guy was one of our doctor's at KU.... don't know for sure though. He spent a whole lot more time talking about transplantation in general than he did his research, but it was pretty obvious that he was very interested in how mismatched transplants were less likely to have cancers/myelodysplasias down the road.

 

[R_C_Hutchinson]

Cool, thanks guys. Much appreciated for the info.