This arm would be the death of her.

Imogen clenched and unclenched the claw where her left hand should be, emerald ribbons of magic weaving between the scaled talons and knobbed joints. The blood of a dragon flowed through this cursed arm and into her veins, blessing her with the touch of magic and cursing her with endless pain. The mountain range of human skin buckling against the mass of scales along her shoulder forever ran hot and red. She’d almost died the first week of bonding to this cursed blessing before they’d gouged her with medicines to keep her body from fighting off the arm tissue, and her own tissue with it. The kingdom’s strongest mage had one weakness, and that was her own body.

And they placed the kingdom’s strongest mage, who could drop dead at the smallest hint of a fever, in the middle of a bloody camp. The filthiest place in the world. Imogen pressed her mask tighter over her mouth and nose as she was led past the medical tent. Wonderful. She’d always wanted to die of typhoid.

Her guide, some low-ranking officer whose name Imogen had already forgotten, cocked their head to catch a glimpse of the famous draconic arm. Imogen pulled her sleeve even lower. “Rumors say the arm’s a thousand years old.”

Imogen flinched away from a nearby sneeze before she shrugged. “Sounds like a legendary tale,” she said, her mask muffling her voice.

“So is it?.”

“Use your brain. I’m barely surviving off of this living tissue. Lugging around that much necrotic tissue would send me ten meters under.”

The officer led her past the last tent and nodded. An onyx plate had been excavated with ancient, indecipherable markings. Or “currently-indecipherable,” Imogen reminded herself. The general had requested a “reveal” spell to identify it before the army continued on past it.

The sooner she cast the spell, the sooner she could leave. Imogen’s scaled claw lifted and drew three circles in the air while she whispered the incantation. Instead of summoning glowing scripture translating the name of some poor bloke’s long-lost grave– like Imogen had hoped– the carvings glowed scarlet and then a streak of red light shot out from the slate and into the dark, dense woods.

Of course it wouldn’t be simple. Of course the spell would make them trudge through bug-infested swamps. Imogen turned back to the officer. “Tell your superiors they’re paying for my immunosuppressants after this,” she said.

—

Hello all of you beautiful people, you curious critters!

It’s me! I’m back! And coming out of the gates with an immunology blog post, no less! Oh, how I’ve missed this!

Ah yes. I should probably get to the post, shouldn’t I? Alrighty; let’s cease these celebrations and dive right into it!

We’ve seen this plenty of times before in fiction, where the character loses an arm or a leg, and they get gifted a new, biological limb. It’s just as good, if not better (or even magical) compared to their original limb. Now they can cast spells, or jump great distances, or even shapeshift their new limb for whatever the situation requires.

Correction: we’ve seen this plenty of times in fictional games. I can name quite a few video games that . I’ve seen countless player characters from tabletop role playing games that have an arm or a leg replaced with a monstrous replacement. From a game mechanics perspective, this limb addition is working double duty. The new limb explains the outrageous abilities the character masters while simultaneously providing a unique silhouette for character design. In Tears of the Kingdom, Link’s transplanted Zonai arm allows him to reverse time, levitate, and fuse items together. Violet’s transplanted demon arm in Tales of Beseria allows her to use demon powers. Melinoë’s transplanted ghost arm in Hades II does… okay, I don’t know yet, but I’m sure it does something cool (I’m currently avoiding spoilers for the game, so don’t tell me if you’re playing it in early access!)

And HOOOO BOY, transplanting body parts in comics and cartoons, especially anime? Examples abound! Points directly at Naruto manga’s Itachi and Sasuke and Danzo. If you know, you know.

But in books? I don’t think I’ve seen this trope. I’ve seen prosthetics, but I can’t recall ever reading about any characters with transplanted body parts. Prosthetics? Sure, but nothing like replacing your sword arm with that . If you’ve read a book with this in it, though, let me know because I’d love to read it! I’m sure they’re out there, I’ve just missed them by luck.

It was while playing Tears of the Kingdom, though, that got me thinking: would the hero Link die from his new arm?

(also, I couldn’t find any royalty free images for grafts and transplant, so… Imagine!)

What is A Transplant?

—

So, before we can ask whether or not our hero will survive his arm, we have to understand how it would kill him. And to do that, we have to understand the biology of a transplant. This is taken directly from my graduate school immunology notes and the 9th edition of Janeway’s Immunobiology textbook (chapter 15, specifically).

A transplant, simply put, is the replacement of diseased/damaged tissue with healthy tissue. You’ve probably heard of a kidney transplant, a heart transplant, and even a blood transplant if you’re like my family and like watching doctor drama shows. Or perhaps you’ve stumbled across a news story covering a kind soul donating their kidney to a patient after a fateful meeting. Transplants are commonplace in modern day medicine, but would they be so commonplace “ye olden days” that many fantasy

Skin grafting, according to this article here, has been around since 1500 BC, where in Ancient Egypt to “[bridge] over skin defects,” as documented on the “Ebert Papyrus” roll. I wasn’t able to find whose skin was grafted onto whom, which is a key question when considering transplantation, but in 1869, a surgeon was able to successfully use a skin graft from the small bits of a patient’s arm to fix a wound. Anyone in the medical field would recognize this as a “pinch graft.” During World War II, a pilot with 70% burns over his body had a massive skin graft, taken from that of a recently deceased patient. The surgery was shockingly successful, as they anticipated his body to reject the graft, and the pilot lived to be 84 years old.

And that’s all skin grafts. We could be here for hours if I delved deep into the history of transplantations, but the point is that grafting is both new, and yet ancient. What we can graft has grown to where we can transplant hearts, lungs, and even faces.

So with modern medicine, we can replace an arm for an arm no problem, right? Not exactly.

First, we have to consider what kind of transplant we’re dealing with. The donor and recipient are the same (ex: Skin Pinch). The donor and recipient are genetically identical (ex: a limb from an identical twin). Donor and recipient are genetically different but of the same species (ex: kidney transplants) Donor and recipient are genetically different and of different species

If we’re looking at our hero Link’s cool, magical arm, he has #4: “Donor and recipient are genetically different and of different species.”

Right off the bat, it’s not looking good for our hero. Let’s dive into why.

The Immunology of a Transplant

—

Did you know the cells in your body have a barcode?

On the outside of all of your cells, you have receptors called MHC receptors. What you need to know is that the job of the MHC receptors is to take proteins from inside the cell, and hold it out for the immune system to see if a virus has gotten into the cell. The most important part of the MHC receptor for this blog post is that MHC receptors stick out of your cells for T-cells to interact with.

T-cells are some of the immune cells that float throughout your body, searching for any possible viruses floating around that can make you sick. T-cells do this by attaching to the MHC receptors and checking to see what’s attached on said receptors. If the MHC receptor is holding onto virus proteins, your T-cells are activated and start calling onto your immune system to start reacting to the virus!

Now, where does the “Barcode” come in? You see, those MHC receptors have a unique bunch of proteins on them that the T-cell can “scan” to check to make sure the cell the MHC is sticking off of is your cell, and not someone else’s.

If that “protein barcode” is off, the T-cell sounds the alarm to have your immune system start attacking this alien cell. You start making antibodies to that alien cell, and soon your immune system in a full fledged assault against this alien tissue.

Going back to our hero with a different species’s arm, the likelihood that Link’s immune system will recognize a completely different species’s MHC receptor as “self” is slim to none. He’s not dead yet, but he’s going to need help to keep his body from completely rejecting his new arm.

What Happens if The Transplant is Rejected?

—

Most of the time, transplanted tissue and organs will result in some degree of a response from the immune system.

There are two main kinds of responses: 1) Host Vs Graft disease 2) Graft Vs Host disease

Yes, these seem like the exact same thing and me listing them looks redundant on paper, but they’re actually very distinct in how they function at the microscopic level.

In Host Vs Graft disease, the body receiving the graft sees the graft as foreign and a threat. Time to roll out the immune system’s defenses! And like that, the host’s body actively tries to pry off the graft through immunological warfare.

In Graft Vs Host disease, the transplanted tissue brings along a functional group of T-cells. Remember, the person the tissue originated from had their own immune system. That group of alien T-cells can join the party and start treating the host as the threat. These alien T-cells can start killing off the host’s immune system.

To keep the immune cells from destroying the host and/or graft, patients can be given Immunosuppressive drugs. As the name suggests, these drugs keep your immune response chill, keeping your body from responding with T-cells, antibodies, etc.

This isn’t great. People who take immunosuppression drugs are considered “immunocompromised.” While your body won’t be attacking the life-saving graft (or vise versa), it also now can’t defend against actual threats like viruses and bacteria.

So back to our case-study hero: Would Link have Graft Vs Host, or Host Vs Graft disease? Hard to say, but my guess is on Host Vs Graft disease as the arm Link has is a couple thousand years old and most likely doesn’t have any functioning T-cells left?

(Honestly, it’s a miracle that the arm has functioning skin, nerves, and muscles after 1000+ years, but we’re letting that slide for the sake of coolness).

But in any case, unless Link has immunosuppression drugs, that arm’s not going to last long.

Checks Legend of Zelda History. Besides literal resurrection magic and general healing magic, there’s no mention of medical advances in any of the Legend of Zelda series. My understanding of healing magic is that it stitches up wounds, but I’m not sure how it’d work to suppress one’s immune system. That sounds like the opposite of what the magic was designed to do. And in our specific Link’s game, he’s still in a post-apocalyptic setting, so my guess is that he’s fresh out of luck for finding the necessary medication he needs to keep his arm.

Wow… this may be the one game where Princess Zelda’s plans actually will get the Hero of Hyrule killed. I guess she really wants her own main-title game.

Takeaways

—

I’m really kicking myself for not thinking of any book examples of limb transplantation. You’d think I’d have run across it in my science fiction reads, since those stories have access to modern medicine and then some, but nope. I can think of limbs being replaced with robotic prosthetics, but not full on functional organs.

And yes, using grafts is technically easier to incorporate in science fiction stories, and should be used more, but where’s the challenge in that? Heck, even tackling the process and repercussions of getting a kidney transplant in any setting has plot potential!

If you’re tackling the topic in scifi, you could explore what it’s like when the body starts to reject the new organ even if your character is taking the proper medication; it can certainly happen. If your story’s in a more “classic” fantasy (pre-industrial flavored), you could explore folks developing the surgery, discovering the proper immunosuppressants, or even developing magic to function in place of medication. As our own history clearly shows, the concept of grafting wouldn’t be completely foreign to this sort of setting.

Anyhow, that’s all I have for you lovely folks! Such a fun topic to start off with on my return to blogging! See you next time!