Why does only some types of transplants – organs, require the recipient to take anti rejection meds? Why isn’t it required for things like cartilage or skin grafts
Edit for typos
In: Biology
Okay, so big picture: every cell in your body is covered with [MHC markers](https://en.wikipedia.org/wiki/Major_histocompatibility_complex). These help the body differentiate self from non-self. When the immune system sees something that is non-self, it may attack. (In the case of bacteria, that’s good. In the case of allergens, that’s bad.)
When transplanting, the most important rule is that you never transplant MHC markers into someone who lacks them. That’s like sending someone into a bank wearing a shirt that says “BANK ROBBER”. The immune system will attack.
Now getting to your specific question:
Skin grants [from one person to another require immune suppression](https://www.sciencedaily.com/releases/2014/11/141118105630.htm), as do grafts from one species to another. The only type of skin transplant that doesn’t is an autograft (transplating skin from one part of a person’s body to another), because that new skin is a perfect match (e.g, it has exactly the same MHC markers the immune system is expecting).
Blood transplants (aka, transfusions) don’t require immunosuppression because blood has the simplest of all MHC marker systems. There are only 2 major proteins (A and B) so it’s relatively easy to find a perfect match.
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