Basically it's just saying that if you take a particular genetic sequence and introduce it into foreign cells, you can put them into a body where you'd expect an immune response (t cells), but in fact you actually see those cells die instead (apoptosis).

It's too bad it didn't turn out to be true as it would have been an incredible advancement in transplantation.

Yes, exactly. It's a pretty straightforward statement -- if you know what the words mean, and why it's significant. If you don't have that background knowledge, it's completely opaque.