[rdmirza]

That’s a great thought, however, when you look at tissue under a microscope you should see evidence that the immune system was at play. This means the presence of complement activation (an ancient arm of the immune system), antibodies, white blood cells, nuclear debris, and so on. Presumably when they saw no evidence of immune mediated rejection, they saw none of this.

[DoreenMichele]

My lay person understanding as someone with a condition where people get a lot of transplants is that we don't actually know what causes rejection.

Perhaps in some cases the organ contains unidentified infective agents, thus the typical pattern with white blood cells etc.

Perhaps in this case the body decided it was straight up foreign matter and the process of failure was fundamentally different.

[balanoceous]

Your point that this is uncharted territory is well-taken, we can't say for sure, but the above poster has it right. I do not know of any circumstance in medicine in which evidence of immune reaction against foreign material would be non-obvious. I'm a pathologist and this is my area of expertise.

[polishdude20]

What if it's something like the human blood cells stop delivering oxygen and nutrients to those tissues for one reason or another?