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Comment by waterhouse | Hacker News Reader

Ignorant question: is it possible to have something resembling a human immune system without a full body? One level would be just a container of liquid with live white and red blood cells, possibly connected to an oxygenation machine; you would insert some infected cells, then sample it or otherwise observe it periodically. If you need lung tissue or other non-blood cells for the virus to infect, then having disembodied blobs of flesh with blood vessels, being fed nutrients and oxygen, would be the next level.

Of course, if this testing infrastructure doesn't already exist, I imagine creating it would be too slow to help with this particular plague.

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this is sort of how HIV production works in the lab, as it was explained to me. CD8+ cells (iirc) in solution with some other cell types/buffer medium are infected with some population of HIV particles, and the infection spreads to the other cells. this helps researchers see whether certain strains are replication-competent etc. you don't really need the red blood cells or oxygenation machine.

there's other approaches to make "organs on a chip" for drug trial screening, since lab models with only one type of cells don't capture the effects of other types, but it's really not fully baked yet.

No. The immune system is incompletely understood and staggeringly complex. It’s not a single performer or a band: it’s a symphony. You can examine individual parts to your heart’s desire, but the true nature of the immune system arises in the emergent properties of the system.

Your “first level” is something we already do with primary and immortalized cells and it can be a useful model. Your next level would be called co-culture and it also is something we already do. These can be static cultures or connected to flow systems or bioreactors or whatever. These are imperfect models, but they can help to yield useful answers for questions in the model’s scope. The closest fidelity to human immune systems would be animal models, and the closest of these would be Rhesus macaques, and indeed these are used for vaccine development.

Probably it is, but it isn't within our current knowledge.

I know you prefaced your ignorant question with "Ignorant question:", and I don't think it's wrong to ask questions of experts on HN. (That's one of the best things about this site!) However, I'm downvoting you anyway because, despite that preface, you seem to be falling into the trap of a smart geek in one field vastly (vastly!) oversimplifying the complexities of another field, and acting as if all we needed to solve this problem was for someone like yourself to come up with this fantastic idea.

No, you can't approximate a human immune system with red and white blood cells in a container of liquid. No, adding some other cells in there won't help. If that were effective, we'd be doing it already. You are either overestimating your own ingenuity or underestimating the ingenuity of tens of thousands of scientists, doctors, and engineers.

Alternatively, OP could be answered by someone saying that this is already being done. And apparently it is in some form, according to a sibling comment of yours. Maybe that’s incorrect, but you chose the least charitable interpretation instead of “Hey, here’s an idea. Why doesn’t it work like I think it would, and does it have any uses in any form?”

The question was, "is it possible to have something resembling a human immune system without a full body?"

The answer is no, for somewhat obvious reasons. The human immune system involves many organs and tissues and cells working together in very complex ways.

And I think your charitable interpretation is quite a bit too charitable. OP did not say anything like "why doesn't it work like I think it would".

My last sentence shows that I don't think my comment is going to save us from (or even help with) this pandemic. I also chose to ask it in a thread towards the bottom where the OP is answering not-new concerns. I think you have pattern-matched me (well, you say as much) and have read some intentions into my comment.

For the record, my main intention was to get an expert to say something that would gratify my curiosity and that of other readers. I hadn't heard of it before, so I assumed it was likely impractical at the moment, but guessed that technology would eventually get there.

Also, are you an expert in this field? Your sibling comment seems to be saying "yes they are working on it, no it's not practical yet except for HIV" (I presume because HIV infects white blood cells), which is at odds with your second paragraph. (Edit: Though, to be very precise, the examples from the sibling comment are about measuring infectivity and—I guess—the impact of drugs, not immune response.) It would be ironic if a non-expert gave an ignorant dismissal of a question for being ignorant.

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