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

Replaced is a bit of a misnomer. A million cells in your body die every second. The “replacement” cells are generated through mitosis, where a cell duplicates its DNA and separates itself in to 2 cells. So your body produces new cells from the previous existing cells, all containing your DNA. A transplanted organ does the same thing. Its cells duplicate their DNA and split in to 2 cells. The transplant continues to have its DNA, separate from your own, in perpetuity. Thus it will always be seen as a foreign object and won’t assimilate to your body.