When an organ is replaced with someone else’s, the body needs immunosuppressants because of the foreign object now in the body. Why is the same not true for a blood transfusion?

Question

Basically title! I was wondering about this. Thanks!

In: 144

Answer 1

The blood doesn’t last long in the body which means that it doesn’t need to be as protected from your own immune system since your own body will be producing new blood all the time. On top of that most of what causes an immune system response is filtered out beforehand. Even when that’s not the case there’s not that much of it to begin with so it’ll only generally cause a mild reaction.

Organs on the other hand are full of things that cause an immune system response. On top of that they also contain parts of the donor’s immune system which means that also reacts against the new host. Since the “new” organ is supposed to last a long time immunosuppressants are needed to keep it viable for as long as possible since the host’s immune system will actively be trying to destroy it.