ELI5, how come when you get an organ transplant, there’s a chance your body will reject it and your immune system will kill it. But when you get infected by a new disease, it’s difficult for your immune system to kill the disease.

Question

ELI5, how come when you get an organ transplant, there’s a chance your body will reject it and your immune system will kill it. But when you get infected by a new disease, it’s difficult for your immune system to kill the disease.

In: Biology

Answer 1

The body will always notice a transplanted organ as being from somewhere else and the body does two things with foreign objects. It’ll send in the immune system to attack and destroy, but it’ll also try to surround and barricade the object so it doesn’t interact with the body anymore. The reason transplanted organs aren’t always rejected is because the recipients take drugs to help prevent rejection. When people say “there’s a chance” they’re implying with regular usage of anti-rejection medication.

For new infections, the body will attack if it notices the infection. Not every infection behaves the same. Some infections look like part of your body so your immune system doesn’t know to attack; think penguins walking with nuns. Some viruses hide inside cells to force them to replicate so your body doesn’t see the infection until it’s overrun; this is like a trojan horse attack. Some infections are too strong and go full punisher on your body.