Immune System for Dummies

Saz94

Saz94

Senior Member (Voting Rights)
A thread for people who want to ask questions about how the immune system works.

My question is this: we hear people saying things like "I have a strong immune system, I don't get ill often", or "my husband and I both got the virus but my symptoms are worse because my immune system is weaker than his". I don't understand this because I just read on the BBC that symptoms are caused by your immune system mounting a response to the virus. And that especially, when people get severely ill (like needing to be hospitalised) from a virus, that's because their immune system is mounting too strong a response. So I am confused. Can anybody explain this to me, please?
 
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Sarah94 said:
A thread for people who want to ask questions about how the immune system works.

My question is this: we hear people saying things like "I have a strong immune system, I don't get ill often", or "my husband and I both got the virus but my symptoms are worse because my immune system is weaker than his". I don't understand this because I just read on the BBC that symptoms are caused by your immune system mounting a response to the virus. And that especially, when people get severely ill (like needing to be hospitalised) from a virus, that's because their immune system is mounting too strong a response. So I am confused. Can anybody explain this to me, please?
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Only to the extent that your confusion is well founded. Since we do not understand exactly what they chain of events is in these illnesses it is hard to be sure we know what is due to up and what due to down.

There are some clear cases where we know what matters. So if you have AIDS and it wipes out your immune system you get worse infections with TB or the Kaposi virus. On the other hand for Dengue fever we know that having a strong immune response to one strain makes infection with another strain much worse.

For SARS2/Covid19 having a weak immune system from old age or diabetes looks to make it more likely you will get overwhelming disease. But some young fit adults have died from what may be a lung hypersensitivity response (strong immune response). On the other hand it may just be that they had a high dose of virus (some doctors) and if infection spreads very widely and kills lots of lung cells then the response is nit so much an immune hypersensitivity as just severe damage to cells needed for breathing or systemic toxicity from release of toxins into the circulation as you can get after severe muscle injury in a car crash.
 
Adrian said:
This is something I've been wondering about. Is it that if someone comes into a lot of the virus (high dose) then it starts having an effect sooner and the body doesn't have the chance to start any reaction?
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I don't think there is much in the way of real life evidence on this. The assumption is that if you breath in a million virus particles then it has a head start relative to breathing in one viable particle. A replication cycle probably takes a few hours and multiplies a thousand fold or more so the initial dose might not seem critical. On the other hand there may be a threshold for getting early suppression signals going, like gamma interferon. It may also be that the first replication cycle is in the throat and there is a critical window of time for getting suppression signals going before it starts replicating in lung. But I think this is all theoretical.

What is a bit odd is that deaths seem to occur quite late in relatively robust individuals - maybe after two to three weeks, which rather argue against overwhelming spread early on.

One day people may know!
 
Jonathan Edwards said:
Only to the extent that your confusion is well founded. Since we do not understand exactly what they chain of events is in these illnesses it is hard to be sure we know what is due to up and what due to down.

There are some clear cases where we know what matters. So if you have AIDS and it wipes out your immune system you get worse infections with TB or the Kaposi virus. On the other hand for Dengue fever we know that having a strong immune response to one strain makes infection with another strain much worse.

For SARS2/Covid19 having a weak immune system from old age or diabetes looks to make it more likely you will get overwhelming disease. But some young fit adults have died from what may be a lung hypersensitivity response (strong immune response). On the other hand it may just be that they had a high dose of virus (some doctors) and if infection spreads very widely and kills lots of lung cells then the response is nit so much an immune hypersensitivity as just severe damage to cells needed for breathing or systemic toxicity from release of toxins into the circulation as you can get after severe muscle injury in a car crash.
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Okay, thanks Jonathan. So would that mean that people taking "immune boosting supplements" could actually be at more risk of getting a lung hypersensitivity response?
 
Sarah94 said:
Okay, thanks Jonathan. So would that mean that people taking "immune boosting supplements" could actually be at more risk of getting a lung hypersensitivity response?
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No, because there is no such thing as an immune boosting supplement as far as I know. Even if supplements helped immunity, which I doubt, they are not going to make it more than normal.

The immune system is not like a thermostat that can be turned up or down. It is much more complicated than that. Hypersensitivity can be sign of an immune defect such as a complement deficiency.
 
Jonathan Edwards said:
No, because there is no such thing as an immune boosting supplement as far as I know. Even if supplements helped immunity, which I doubt, they are not going to make it more than normal.

The immune system is not like a thermostat that can be turned up or down. It is much more complicated than that. Hypersensitivity can be sign of an immune defect such as a complement deficiency.
Click to expand...
OK, thanks for explaining.
 
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