Transplant rejection hypersensitivity reactions

Trying to clear up my understanding of transplant rejection and how it works. I seem to be getting slightly different info from different sources.

Here’s what I think is going on. Let’s assume I’m receiving a transplant from you.

Hyperacute rejection - I’ve previously formed antibodies against some antigen present in your cells (your liver or whatever). Within minutes, my body mounts an antibody-mediated attack. This is a type II hypersensitivity reaction.

Acute rejection - Some weeks after getting your fresh, new liver (thanks again!), my cytoxic T cells get all agitated at your foreign MHCs. It’s basically a histocompatibility issue, so we’ve really gotta check those HLA types. Since this is T-cell rather than antibody-mediated, it’s a Type IV hypersensitivity rxn.

Chronic rejection - Months or years later, there’s some vascular fibrosis going on. This is mostly an antibody-mediated type III hypersensitivity, but there’s also some T-cell (type IV) involvement? I’m not really clear on this one.

Graft-vs-host disease - Your immunocompetent cells (maybe from that bone marrow transplant you gave me) start attacking my cells. You cheeky bugger. This is a type IV hypersensitivity rxn.

Hm. So unless I’m entirely wrong on something (which is entirely possible), I’m just confused about the mechanism behind chronic rejection.

Anyone able to help clarify things?

Thanks much!

you got them all right. This is the basis for ensuring that you are as close a match as possible.

Adam, the truthful textbooks all say for chronic rejection: mechanism poorly understood, no known treatment. Just learn the mechanisms for Hyperacute, Graft v. Host, and Acute, and realize that if onset is gradual over the course of years, you’re in chronic rejection.

Sounds good. Thanks, guys.

Random side note: the NBME practice exam (the one they let you download to practice w/ FRED software) is both reassuring and infurating.