I'm Dr. Shruti Naik, scientist and immunologist

and I'm here to answer your question from Twitter.

This is immune support.

HS. Pediatrics ask, can playing in dirt

help your children's immune system?

Absolutely.

So in the field of immunology

there's this idea called a hygiene hypothesis.

We're almost hyper clean now

and that we're over cleaning ourselves

and that microbes are in fact good for us

and they help our immune system

and they strengthen our immune system.

And evidence from this comes from

sort of these remarkable studies done

comparing children that grew up on farms

with children that grew up in city settings.

And the incidents of autoimmune diseases

or diseases where the immune system has gone haywire

are much much lower in the the sort of farm kids

or the rural kids than in the urban kids or the city kids.

Roger Bezanis asks in the 1950s,

the tonsils were routinely taken out

even though they're a fixed part of the immune system.

Why?

Parents were gullible.

Tonsils are a gland that are part of the immune system.

So they are like lymph nodes.

They reside right here and they swell up

when you have an infection

because that's where the immune system organizes.

So in the fifties and sixties,

a large number of children had their tonsils removed

when they were inflamed

with this thought that tonsils

were reservoir where disease struck,

but then the medical establishment

kind of moved away from that

because there was very little evidence

that this was helpful to remove your tonsils

to prevent recurrent disease.

Folks are still undergoing tonsillitis or tonsil removal,

but only in the cases

where they actually have recurrent strep infection

or in some cases of sleep apnea.

Monica Labranche asks what controls your immune system?

What organs or glands?

I am wondering about this.

This is a great question.

So your immune system in fact develops

in your bone marrow from your bone marrow,

also in glands like your thymus, your spleen,

and your lymph nodes.

And these are really centers

where the immune system is acting out of

think of them as sort of fortresses within the body

that unleash immune cells to the rest of your systems

as they're needed.

Zach Weiner asks are viruses alive.

So viruses are this incredible gray area

between alive and dead.

Is a rock alive?

Is this table alive?

No, because they can't replicate

or make more of themselves on their own

without help from another cell, another creature.

So here we have one type of virus

this type of virus infects bacteria,

and right here we have a virus that infects mammals, or us.

What these creatures do is they infect cells,

they hijack, they almost parasitize the resources

of that cell to make more of themselves and spread.

And so we think viruses are this gray area

between alive and not alive

that are really setting our heads for a tailspin.

ImmuneSystemQuiz asks, how do mucus membranes work

as a physical barrier to defend against disease?

The way mucus works is it essentially creates

an even greater separation

between our body, our physical barrier, and the microbe.

And these are particularly important,

for instance in the intestine,

which is densely packed with microbes.

And so the mucus just allows the microbes

to sit in between our intestine

and not even touch our bodies' barriers.

ReverendJake97 asks what does the spleen even do?

So the spleen is this bean shaped organ that's right here.

It does quite a few things.

So it houses immune cells and recycles iron,

and it also gets rid of your red blood cells

that are pretty old.

You don't need a spleen,

surprisingly if you get rid of your spleen,

the liver takes over a lot of the functions of the spleen.

So again, our body is really, really adaptable.

It's a very fine tuned machine.

M'lis Company asks is chicken soup

good for the immune system?

What natural remedies do you use to combat sickness?

I'm a scientist,

so my answer's gonna be a very scientist answer.

I don't use natural remedies to combat sickness.

I use what we call empirically tested medicines.

One thing we need to think about

when we think about medicines

is how these medicines are developed,

how they're rigorously tested.

I don't think that kind of study

has been done with chicken soup yet.

And so it's very hard to say

does this actually work in a medical setting?

Is it delicious?

Does it taste good?

Of course.

Pyramids RM.

The immune system consists of a group of cells,

tissues and organs similar to the army

and each of them performs specific functions

to attack any enemy storming the body.

So how does the system work?

So first of all, I just wanna congratulate Pyramids RM

on a beautiful analogy because it's exactly how it works.

The immune system is essentially our safeguard

against invaders.

And the second we have an invader, a pathogen, a virus,

a bacteria that crosses our boundaries,

the immune system can sense

this pathogen consensus disturbance and respond

and try to kill it, eliminate it.

Troyella5 asks questions for #immunology Twitter,

I didn't know there was a hashtag #immunology Twitter.

If antibodies to #COVID19 don't last very long

in the body, how effective can a #vaccine be?

Really great question.

Really important question.

So yes, antibodies don't last very long

because they are proteins

and proteins are not very long-lived,

but what are very long-lived are cells.

And so the cells that make the antibodies,

we call them memory B cells, are very long-lived,

and in fact live for decades sometimes

following certain types of vaccinations.

So those are the powerhouses that last a long time.

And so even though your antibody titer

or the antibody levels may decline,

the cells that make those antibodies

are being stored and being preserved.

Tampa Bay News asks the thymus gland,

how does this little known gland help your immune system?

So the thymus is a very, very important gland, in fact

because it is where a key type of immune cell develops,

the T lymphocyte.

So the T lymphocyte is part of the the T-cell

or the T lymphocyte.

And I think I have a picture of this guy here.

It's this little cell.

It's actually really an important part

because it helps directly kill virally infected cells

and it's also being harnessed to fight cancers.

The thymic gland is right here.

It sits right above your heart, below your sternum,

and this is where these T-cells develop

where they form, where they learn,

and then they're sent out to the body to patrol.

So Neecye asks, does anxiety and depression

have an effect on your immune system?

The immune system and the nervous system

are much more closely connected than we realize.

When you have an inflammatory reaction,

your nerves activate.

And in fact, there are some really interesting early studies

that show that memories of immune systems

are remembered in our brain.

And inflammation are remembered in our brain.

And also there's a lot of evidence suggesting

that when you're stressed,

you have essentially more vulnerability to infections,

you have more vulnerability to inflammation.

There is this interconnectiveness

that's now starting to be unveiled.

JoeBabychase asks, what are lymph nodes?

Lymph nodes are the centers

that are basically fortresses throughout our body.

They're glands throughout our body

that aggregate the immune system.

So all of our tissues are constantly being monitored

by immune cells.

And these cells will flow into the lymph node

when there is something bad like a pathogen going on

where they can orchestrate an immune response.

And you can think of this as sort of a border

with a fortress.

There's, you know, soldiers at the border

and if there's some, there's something bad that happens,

sentinels go back to the fortress

where they can organize a larger army

and then send them out to the border to fight.

NHMAmd asks, how could people with HIV

live a healthy lifestyle?

What's amazing, and again, credit to medical science

is that HIV is no longer a death sentence.

We have a number of different drugs that control the virus

and in fact can keep viral numbers in the body so low

folks with this infection can go on

to live a very healthy life.

Anti-retroviral therapies and preventative measures

like Truvada have really helped limit the infectious effects

and also the transmission of this devastating pathogen.

Nicole Hallinen asked specifically where does the waste go

after a macrophage eats bacteria or virus?

Is this why people sneeze and have extra mucus?

Does it come out in urine?

Okay, good question.

So first let's talk about what a macrophage is.

A macrophage is a cell of the innate immune system

and it's actually a cell

that is essentially like the garbage collector of the body.

You find macrophages all over your body

in every tissue everywhere

and they're really good at eating dead cells, dying cells.

They're really good at eating bacteria.

The macrophage is remarkable

because it's not only a garbage truck,

but it's also helping break apart the bacteria,

kill it, disintegrate it, and get rid of it.

Andileinenberg asks, why do fevers always spike at night?

How do they know that it's night?

So our body has a remarkable system.

It's called a circadian clock.

It's a cyclical clock that's within all our cells

that kind of gives it the sense that it's day and

or it's night and the cells behave very differently.

And so one of the reasons fevers spike at night

is because your cortisol levels, your hormones

are really, really controlled by this clock.

And cortisol suppresses inflammation, suppresses immunity,

and so at night the cortisol levels go down,

and your inflammatory response goes up.

And so this is sort of the natural circadian clock

and so you feel fevers more at night.

Lindy2350 asks, asthma is defined as a lung disease,

but is it also accurate to call it a disease

of the immune system because similar to allergies,

it's sparked by an overactive immune response/inflammation?

That is correct, Lindy, or I guess Melinda.

Asthma is a disease that manifests in the lungs

and it affects your breathing,

but it's a disease that's caused

by hyperactive immune cells.

These immune cells are once again cells

that where the break has been taken off their activity

and they're sort of turned on and behaving in a manner

as though they're trying to get rid of a pathogen

or a bad guy.

But in fact, this time

they are causing lung disease or asthma.

kharliii with three i's asks, I hate having psoriasis.

Like what the explicitive even is psoriasis?

Where did it come from?

Why do I have it?

Psoriasis is an a disease or condition,

which manifests as sort of scaly plaques, redness, itching,

swelling, and the underlying cause of this disease

is a miscommunication between immune cells

and your skin cells.

The immune cells think they're fighting a pathogen

or they're helping repair tissues

when really there's no pathogen or tissue repair needed.

Thesquattingman asks, what does autoimmune even mean?

Once again, it's in the name, autoimmune.

So self, auto itself, and immune.

So autoimmune is when your immune system now

instead of activating and fighting pathogens

is recognizing your own cells, your own proteins as bad

and attacking them.

So one example of this is diabetes

when your immune system thinks

that your cells that make insulin are bad guys

and attacks and kills them

and so you're no longer producing insulin.

Surt_lab, question for immunologists.

Outside of the recognized genetic disorders,

what's known about person to person variation

in immune function.

Thinking about when people say

I have a strong immune system,

I never get sick.

It's a very astute question

and it goes down to this fundamental property

of nature versus nurture, right.

How much of the way our body works

is encoded in our genes, our DNA, that code that makes us,

and how much of it is the things we're exposed to

in the world?

And turns out the immune system

is one of those remarkable systems.

It senses the world, it learns from the world.

And so it's really, in a large part

its function is determined

by all of these extrinsic factors

in a really dramatic way.

So evidence for this comes

from studies that are identical twins.

So we know that these twins have the exact same genome,

exact same DNA because they're identical.

Folks have looked at the immune system in these twins.

And what they find is that there's remarkable differences

in the way these immune cells function,

in what types of immune cells there are.

And so what that tells us is even when your DNA

is exactly the same,

your experiences has a huge tremendous impact

on how your immune system works out.

Outflanked asks so anti-inflammatories bring down fever,

but fever is part of the immune response to fight infection.

Does bringing down a fever prolong recovery?

This is an interesting question

because yes, fever is part of the immune reaction,

and though the thought behind it is

that pathogens are really good,

they're adapted to our body temperature.

So if the body increases its temperature,

it's no longer hospitable to a pathogen.

And so that's one way by which the body

is trying to get rid of this pathogen.

But what we have now are really remarkable antibiotics,

antifungals, antivirals.

And so we use those to eliminate the pathogen.

And so the fever strategy may no longer be necessary

and doesn't really affect the prolonged recovery.

And finally, Dr. Karl, can you catch the same cold twice?

Yes, you can absolutely catch the same cold twice.

And I wanna clarify, you know,

if you're vaccinated against a cold,

you can still catch a cold.

But what happens is your body has learnt

to deal with this bad pathogen,

whether it's a virus, whether it's a bacteria, whatever.

And so the second time you catch it,

chances are you're gonna clear it much, much faster.

And we know this and certainly the examples with covid

have been very clear where once you're vaccinated,

the numbers of folks that were hospitalized

that were really experiencing severe disease

was much, much lower

because their immune system has now been educated

on how to control the pathogen.

That's it.

That's all the questions and I hope you learned something.

Until next time.