Do any other potential causes of disease initiate an immune respose at low doses?

[Isaacson]

If I understand correctly, low doses of most viruses initiate an immune response, which is how vaccines work, I also think I've read somewhere that low doses of some bacteria can help to "train" the immune system to make it more capable of dealing with larger exposures later on.

 

I was wondering if this was true of any other potential causes of disease like carcinogens or poisons, where a very small dose over time actually makes the body more capable of defending against a larger dose later on.

 

With regards to poison, I'm not referring here to the fact that some poisons are good for you in low doses and poisonous in high doses. I'm specifically asking about ways in which small doses of a thing actually help protect you against larger doses later on.

 

Thanks.

[PhilGeis]

Think you're misinformed. Viral vaccines are typically based on inactivated/killed or live attenuated (weakened) organisms. I'm not aware of immune response from exposure to sub-infectious doses.

[Elite Engineer]

Dose relative to a poison and maybe carcinogen makes sense..but for full fledged viruses, it does not.

 

In talking about poison, there has been documented evidence that small amounts if poison, over time, can help you build a sort of enzymatic resistance to it. However, I'm not sure of the exact mechanism..and its more likely to fail than to succeed. What if you tried to somehow make yourself immune to cyanide. I can't even begin to think of what proportions would be safe to inject. As for arsenic, there has been some development...but doesn't mean it's safe. For example, a small Andes community was found to have a mutated enzyme that was capable of methylating arsenic, thereby reducing it's toxicity. (Story here-->http://www.iflscience.com/health-and-medicine/population-found-adapted-arsenic/).

 

As for viruses, they have to be inactivated/ killed, as PhilGeis said. When your body builds an immune response to the virus..it's developing antibodies to the specific foreign protein the virus has...not the "small" dosage of the live virus. There's no real "dose" of a live virus that would make you immune, mainly b/c some viruses are extremely dangerous at any concentration. That's like saying, "Lemme give you the smallest dose of HIV". Doesn't matter how small it is...you're going to get infected.

[MonDie]

Inflammation is a manifestation of the immune response. Inflammation can be induced (through unhealthy foods) or reduced (e.g. with corticosteroid drugs), but it is not part of an adaption to those things AFAIK.

 

The answer will probably hinge on whether the threat produces antigens, but beyond antibodies I'm not sure how either/or the answer will be. The immune system "learns" to produce highly specific antibodies in response to previously encountered antigens, but I'm not aware of any other evolved adaptation that "learns" in the way the immune system does -- one of the "experts" might know of something. You could postulate that a certain amount of natural selection might occur on our cells as we're exposed to different chemical agents, but I highly doubt that this would constitute much of a defense in comparison to the evolved adaptations that evolved to counteract that particular threat.

Edited December 13, 2016 by MonDie

[Function]

I'm no expert whatsoever, rather a rookie, but let me give it a try ...

 

First of all, unhealthy food does, generally spoken, not induce inflammation, but may contribute to it (cf. omega-6 fatty lipids), as far as I'm aware of. Leaving alone food contaminated with pathogens.

 

Second, an inflammatory response needs an inducing mechanism. I'm not going too far in to details - mostly because I've forgotten most of it by now, I have to recap this matter for my exams in January and haven't given it attention anymore since Octobre - but you'd first of all have to understand that all normal human cells express a certain membraneous protein, of the HLA-E family.

 

Long story short: NK-cells (natural killer cells), some sort of white blood cells, act by recognizing the absence of HLA-E on membranes. That's a first mechanism how our own immune system (quite innate, not adapted) fails (luckily enough) to attack our own body. NK-cells kill other cells with granzymes and perforins (cf. MAC-complex described below)

 

But before NK gets there, pathogens are bound by "complement factor" C3. I should recheck what this specifically induces, but I recall that it acts by activating C5-C9 (other complement factors), collectively called a MAC-complex (membrane attack complex; forgive me for saying complex twice), inducing holes in the cell membranes of the 'victims'.

 

Again, your own cells express some proteins at their membraneous surface (it had to do something with "H" or "I" in its name ... or was it "F"?), which cleave the C3-complex upon binding, preventing it from telling MAC to destroy the cell.

 

Finally, the selection of T- and B-cells ... Now this is really complicated, but to make a long story short and over-simplified: in the maturation of T- and B-cells (so when they aren't up to fighting against anything harmful yet), they are being exposed to human proteins. Now, if I recall correctly, but this is something I'm absolutely not sure about anymore, there's this AIRE-thing in your thymus, responsible for expressing all human proteins you could ever imagine, you'd ever make or you'd ever made. Complex mechanisms: when an immature T-cell, which undergoes maturation in the thymus, binds a protein of which its production is induced by AIRE, it goes in apoptosis. If it would happen that it'd still survive its own thorn of apoptosis, and later bind a human protein, it'd probably go in anergy (state of uselessness, followed by apoptosis).

 

Comparable mechanism for B-cells. I guess. Everything else gets the full-blown thorn of the innate and adapted immune system.

 

But I'm not sure about these mechanisms anymore. Ask me again on January 20 (then is my exam on infections and immunity).

 

Sorry! Happy Hunger Games!

 

Oh, and Merry Christmas!

 

EDIT: oh my silly me ... I thought MonDie's message was the OP ... How did that happen ... Ah well, I'm not going to delete everything, enjoy the knowledge and its potential flaws!

Edited December 24, 2016 by Function