If most organ cells, like in the liver, are replaced every three years or so, why isn’t a transplant eventually accepted by the new body?

Question

If most organ cells, like in the liver, are replaced every three years or so, why isn’t a transplant eventually accepted by the new body?

In: 350

Answer 1

Let’s take a liver as an example. Each cell contains a string of DNA that acts as a recipe for various proteins. These proteins are what the host body sees as foreign and attacs, because it is produced from another DNA recipe.

When a cell “reproduces” it splits in two, each one keeping a copy if the original DNA. In effect the liver will keep the donor DNA for ever.