Just in case…this is not an anti-vax question. I believe vaccines to be the most important medical discovery in science. Outside of the yearly flu shot I’ve had all my recommended vaccines.
As I understand it, vaccines work by teaching your body to recognize a particular virus to combat it. Is there some sort of limit to the number of viruses your body can learn to fight? Given the number of viruses in the world I would expect, if it exists, to number in the hundreds, if not thousands.
There is going to be a theoretical limit, as for each pathogen the body must maintain memory T and memory B cells specific to that pathogen in order to maintain immunological memory. The pool of these cells is going to be finite, but I can’t even hazard a guess as to the actual amount of pathogen data the immune system can hold.
In short, there is a limit, because the body can only hold so many of these memory cells and each memory cell only protects against one specific antigen. You need a pool of specific memory T cells for each specific antigen to maintain immunity, but the body an only hold so many of these cells and maintain homeostais.
There’s a meme running in the anti-vax crowd that some doctors advocate giving an ungodly number of vaccines to children. This is in fact a gross distortion of an estimate published by Paul Offits et al. (Full text) who was trying to answer the very question you ask.
Their conclusion? Theoretically, you could give up to 10,000 vaccines at once. Over a lifetime, I think they floated the number 100,000.
I have to admit, I’m a little surprised by those numbers. I would have guessed the 10,000 vaccines at once lower and the 100,000 in a lifetime higher. I’ll bookmark your cite for later reading. I’m not even remotely disagreeing with you, understand, it’s just… huh. Fascinating.
The total theoretical antigen “memory” is much higher. From the paper:
The 100,000 figure was mentioned in interviews with the author, and I can’t find any hint of it in the paper.
What we really need to answer the question of the theoretical limit is the minimum number of memory B and memory T cells required to maintain immunity for a single antigen. I don’t know if anybody’s ever calculated that, but I suspect there isn’t a decent number because not all antigens are created equal. It starts to get real, real complicated.
Take Hep B and HIV for example. I have the vaccine for Hep, and I don’t have HIV, but let’s forget about that for a sec. Hep B is a lot meaner from an exposure standpoint. Even if there was a vaccine for HIV, and the patient’s body was “immune”, it’s going to take a lot more cells to combat Hep B than it would for HIV simply because HIV is fragile. HIV takes far more individual viruses to cause an infection. Orders of magnitude higher. That’s going to screw up any calculations you could possibly do.
Also, there’s other antigens that aren’t pathogens. How much of the immune system’s total data is taken up by stuff like pine pollen and pet dander? Those are antigens too, so it makes the calculations of a theoretical limit regarding pathogens very, very problematic.
This isn’t really how B and T cells work.
The B cells, at least, start out their lives with a particular epitope they are sensitive to. (the epitope is a molecular shape that is foreign to your body, the B cells that would have attacked you get screened out in the bone marrow, usually)
It’s a parallel system - if you gave someone 100 different vaccines at the same time, 100 separate B-cell systems would react to them.
The problem is that certain compounds emitted by the immune network will cause systemic responses, such as fever, and so 100 vaccines would cause you to probably develop a dangerous fever and too much inflammation.
However, if you gave someone the vaccines a few at a time, they would probably be just fine.
Don’t kid yourself, however. Vaccines are not as safe as drinking tap water. The immune system isn’t a foolproof systems, and sometimes it can react to a vaccine in harmful ways. Frequently, they mix in parts from bacteria that humans have a long established immune response to boost the effectiveness of the vaccines. The immune system reacts very vigourously to these adjuvants - sometimes too vigorously.
The thing is, you can selfishly refuse vaccines for yourself and your children, and, due to herd immunity, you probably will not get sick. You avoid the risk of the vaccine, which isn’t 0, and you don’t get sick either.
The problem will occur when too many people cheat the system and the herd immunity becomes weak enough that these diseases start spreading throughout the first world populations again. Then you’re in trouble if you didn’t get the vaccine.
True, but the more that I think about it, it’s is T-cells that are more important in lasting immunity. The B cells are more short term. They fight the initial infection, but it’s the T’s that remember it afterwards. Well, there’s a shitload of different types of T-cells, but long term immune memory is kept in a type of T cell. Additionally, the memory T cells also start out as specific to a particular antigen.
I guess we need to talk about hyper mutation here. This isn’t directed at deeg but rather everybody who might be interested and I’m going to try try to keep it simple, so some of the the science isn’t going to be all that precise. When a challenge to the immune system occurs, a lot of different types of cells start dividing like crazy. A subset of B’s and a subset of T’s will “hypermutate”, meaning that it’s an evolutionary designed response to try anything and everything that works. Call it a “mediated survival of the fittest”. The mutation rate is about 1 in 1600, and that sounds low, but it’s really high and it happens quickly. The ones that possess a mutation that fits the antigen that caused the initial response stay and fight, the others go away. This sounds like a crapshoot, and it is, but the randomness is actually what makes it effective against novel pathogens.
Memory B’s and memory T’s both do this, but it’s the T’s that stick around and mediate the immune response when that novel antigen comes back. The T-cells are probably the most important thing to look at when evaluating whether or not a particular vaccine works.
But what does this mean? It means that if we want to know the theoretical limit of immunity that’s what we should look at. How much data can the randomly generated memory T cell system hold?
Thanks for the answers all. Interesting discussion.
I’m surprised it’s that high. That would seem to indicate that at one point during evolution there was a time when there was a huge number of invading viruses.
Not necessarily. It’s more a consequence of how the system is designed. The mechanisms are complex, but basically it’s all done by a few cells floating around in your bloodstream. There’s a lot of total immune cells around, because the immune system basically takes a shotgun approach where it tries to identify any molecular surface that is foreign.
Respectfully disagreeing with you; I define those to be sanitation and surgical anesthesia.
Anyway, people have no way of knowing how many viruses and bacteria we’re exposed to on a daily basis anyway. People are more likely to experience vaccine complications from excipient ingredients (this is why people are asked, for instance, if they are allergic to eggs) than they are from the vaccine itself.
The pneumococcal vaccine is 23-valent, meaning that it protects against 23 different mutations.
Which most likely just means that those 23 particular mutations don’t affect the specific epitope that the vaccine is raised against.
I seem to recall reading (back when I was trying to figure out how the body remembered prior infections) that there’s a single (or single group) of cell type that stores all detected virus signatures in a portion of their dna.
Wouldn’t the size of that storage be the limiting factor in remembering immunities?
No, because more cells get made to store specific antigens. And the total “space” is your bloodstream.
I don’t think the capacity of the immune system is limiting. For each vaccine, you need to give a certain minimal dose for it to be effective, and if you add up to many different vaccines, the large amount of foreign material you introduce into the blood stream may cause problems.
I am under the impression that auto-immune diseases result from an immune system that is triggered by a pathogen then finding some body cell that it reacts against, presumably because the cells have some surface similarity to the original pathogen. For example, an aunt of mine had a serious gastrointestinal virus from which she recovered and immediately developed severe celiac disease. She had never had a gluten sensitivity before.
So my question is, is there any correlation between vaccinations and the development of auto-immune diseases?
I can’t speak to what actual data is out there on this, but in theory, there’s certainly a simple path from any immune reaction and auto-immunity, using the somatic hypermutation mentioned above. The idea goes like this: any B or T cell that reacts to any “self” antigen is detected during maturation and dies. This is the body’s standard method of avoiding auto-immunity.
But imagine a hypothetical T cell that manages to mature with a receptor that doesn’t quite react to a particular self antigen. The shape is close, but not close enough to set off the self-reactivity test during maturation. Now imagine that this T cell receptor reacts to some pathogen, so the cell is activated and starts dividing and going through hypermutation. It’s very possible that some of those mutated daughter cells could pick up the right changes to allow it to react to that self antigen. That could certainly lead to autoimmunity.
As I say, I don’t know how well this is supported by data, but as far as I know, the theory is sound.
Auto-immune disease is very complex and not really understood by any medics, least of all conventional Western medics. It’s a hyper-reaction to something relatively small, the molecular equivalent of a panic attack. Did your aunt recover naturally from her illness Hari Seldon, or were there drugs involved? Developing one problem after another suggests underlying weaknesses.
As for vax reactions, read the vax makers’ warnings on the packets. It is both enlightening and not a little scary. Also talk to the parents of children seriously (and mildly) disabled by vax injections. Correlations are high, I wince at the thought of a three month old being given vaccinations - at the least wait until they’re 18 months old - if nothing else the vaccines will be more effective and there is less chance of harming the child.
Utter crap. Disease stems from poor nutrition, poor living conditions, unclean water and a body failing to function as it would choose to given what it needs to be properly healthy. If you live in squalour, eat adulterated, processed food made from an infected, drugged, anti-biotic and chemically-dosed food source then they’re maybe worth consideration. But you’ll have much bigger worries than measles or mumps - cancer and degenerative Western diseases. Our medical ‘healthcare’ is designed to make as much money as possible.
Uhm, no. Polio was a major concern in the US until the 1950’s when a vaccine was developed. I presume you wouldn’t call 1950’s America living in squalor.
Sigh. Here we go again.