[HN Gopher] Immune systems of adults 'remember' germs to which t...
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Immune systems of adults 'remember' germs to which they've never
been exposed
Author : akbarnama
Score : 107 points
Date : 2020-04-22 18:50 UTC (4 hours ago)
(HTM) web link (med.stanford.edu)
(TXT) w3m dump (med.stanford.edu)
| hpoe wrote:
| So I do not understand much about biology but could this effect
| explain why we seem to have so many people test positive for
| anti-bodies on COVID-19 tests, compared to other forms of
| testing?
| vikramkr wrote:
| Likely not, the more likely explanation is asymptomatic cases.
| There is a possibility of false positives and that could be
| driven by something like these nonspecific antibodies so that's
| why I say "likely not" vs "definitely not" and the answer to
| whether it "could" is yes, but whether it "does" I personally I
| think asymptomatic cases are the more likely explanation
| md224 wrote:
| I don't think CD4 cells are the same as antibodies, right? I
| assume that when we test for antibodies, we're not testing for
| CD4 reactivity...
| hutzlibu wrote:
| I understood, that the false positive antibodie tests, come
| from different antibodies against different corona virus or
| just the flu, because they are too similar.
| hirundo wrote:
| "...memory CD4s proliferated and otherwise became activated in
| response to exposure to certain components of the influenza
| virus, but also to epitopes of several different bacterial and
| protozoan microbes. This cross-reactivity could explain why
| exposure to common bugs in the dirt and in our homes renders us
| less susceptible to dangerous infectious agents."
|
| So the CD4 is a key activated to fit a particular lock, but given
| the imperfections of locks it fits a random assortment of others
| too. As we build up a keychain of these we have a better chance
| to fit any random lock.
|
| But why doesn't the larger keychain also increase the chances of
| auto-immune diseases when they happen to fit our own locks? Or
| increase inflammation from other benign microbes it fits? Seems
| like the metaphor needs work.
| nullc wrote:
| > But why doesn't the larger keychain also increase the chances
| of auto-immune diseases, when they happen to fit our own locks?
|
| The process that generates immune cells tests them for
| autoimmune reactivity and aggressively culls ones that are.
| nomel wrote:
| Could you provide the name for this, or something I could
| search for? This is fascinating.
| rcthompson wrote:
| Look up the function of the thymus in T-cell development
| and selection.
|
| https://en.wikipedia.org/wiki/Thymus#Function
| hateful wrote:
| I may have this wrong, but this can also lead to certain
| allergies.
|
| https://www.youtube.com/watch?v=kLC0cX3rAX0
| nradov wrote:
| The hygiene hypothesis might play a role here. Early exposure
| to certain pathogens could have a protective effect against
| autoimmune disease.
|
| https://en.wikipedia.org/wiki/Hygiene_hypothesis
| three_seagrass wrote:
| You do get autoimmune diseases this way.
|
| The thyroid does a good job of filtering out new immune cells
| that attack the body, but sometimes you will get an infection
| where the targeted protein mimics a body protein. When that
| happens, you're stuck with an autoimmune disease.
|
| Example: https://en.wikipedia.org/wiki/Reactive_arthritis
| zby wrote:
| I think you meant thymus not thyroid.
| abainbridge wrote:
| Could someone add 2013 to the title? I just spent 15 minutes
| thinking I must be a genius because I had already figured this
| out. Now I realise I read about it already.
| bsoyka wrote:
| I agree, bit confusing. I never read about it until now.
| Ozzie_osman wrote:
| Could partly explain why it seems like covid-19 isn't hitting
| developing nations as hard. They have more antibodies to other
| viruses. There's also the theory that the tuberculosis vaccine
| (mandatory in many developing nations but not in developed ones)
| helps too, and there are clinical trials going on to confirm
| that.
| chosenbreed37 wrote:
| Sounds plausible. It may be premature to assess the relative
| impact of covid-19 in those nations. Hopefully you're on to
| something though...
| lazyasciiart wrote:
| My impression is that it's being attributed to the smaller
| international travel to Africa in the first place, and then
| that all stopping when the rest of the world locked down. There
| are some pretty wrenching predictions for how they'll go when
| it does start spreading, if that's correct.
| thedudeabides5 wrote:
| It's also warm and wet in many developing nations. Seen a
| couple pieces suggesting COVID is relatively heat-phobic.
|
| Would also jive with seasonality of the flu...
| samatman wrote:
| There's an absence of evidence that this is actually true.
| Tests are in short supply even in places with their own biotech
| industry; countries which are reliant on importing tests have
| no accurate picture of what's happening.
|
| Ecuador is an example which has crossed my radar: ~10,000
| confirmed cases, but overall death rates are way up and they're
| digging mass graves.
|
| We would all love to believe that heat and humidity will blunt
| the spread of this virus, but I'm not seeing nearly as much
| evidence of that as I would like.
| Ozzie_osman wrote:
| Ecuador is actually one of a very few number of developing
| nations that doesn't seem to mandate TB immunization. Iran
| didn't start it until the 1980s.
|
| That said, I agree there is an absence of evidence... It's
| all speculation at this point.
| acqq wrote:
| (2013)
| isbwkisbakadqv wrote:
| article doesn't provide any citation to the article it is
| summarizing...
| jmalicki wrote:
| William Petri is a wonderfully appropriate name for a professor
| of infectious diseases.
| chadlavi wrote:
| love nominative determinism
| techbio wrote:
| There's a term for this!
|
| The orthodontist that adjusted my siblings braces was named
| Dr. Hurt (or some homonym) and I've observed similar many
| times since.
| gowld wrote:
| If you accept few will, it's an aptonym.
| chadlavi wrote:
| Yeah, I assume they're all _really_ aptonyms, but I think
| the other term is more fun
| techbio wrote:
| I don't have a choice but to accept _free will_ :)
| cjbenedikt wrote:
| Don't dish it out...
| kaesar14 wrote:
| Admire the attempt but this just didn't really make much
| sense
| mywittyname wrote:
| It's so agarvating when puns miss their mark.
| [deleted]
| patcon wrote:
| heh, normally how these friendly call-response threads work
| is someone either yes-and's the attempt [1] or
| ignores/downvotes it. Just because we're on HN, that
| doesn't mean puns need to be critiqued -- even if they are
| agaravatingly bad :)
|
| [1]: https://en.wikipedia.org/wiki/Yes,_and...
| samatman wrote:
| It kinda does, though.
|
| I like that HN has a very high bar for humor, and cracks
| down on soft-pitch puns which are an attempt at a long
| chain of groaners.
|
| Reddit exists, and if you like that, you can get it on
| Reddit. Here it's just noise. We have other bad habits ;)
| worldvoyageur wrote:
| I grew up on a farm. It was common knowledge that when a calf, or
| a lamb was born they needed to get that first milk from their
| mom. The first milk looked different and was called colostrum.
| Colostrum contained a large assortment of antibodies from the
| mother that were transmitted to the newborn. If there was some
| health issue, the mother died or the newborn couldn't drink, we
| had colostrum in the freezer. If we didn't give it, the odds
| dropped dramatically of the newborn making it more than a few
| months.
|
| So, yes, mammals, including people, get immunities to germs they
| have not been exposed to.
| cannaceo wrote:
| Those are IgA and IgG antibodies that are being transmitted
| from mother to child. They're effective for a period of time
| until the child's immune system develops but do not confer
| lifelong immunity as the child's immune system creates no
| memory from it.
| Ovah wrote:
| This reminded me of neonatal lupus. Lupus is an autoimmune
| disease where your own antibodies attacks your tissues. In
| neonatal lupus, the newborn is born with lupus ... because
| materal autoimmune antibodies are able to cross the placental
| barrier. So the newborn 'inherits' a lupus condition, which
| usually self resolves within a month once the maternal
| antibodies have disappeared. https://rarediseases.org/rare-
| diseases/neonatal-lupus/
|
| This is presumably applicable to other maternal antibodies,
| which may give immunity against germs the infant has never been
| exposed to. However, this is a 'temporary' immunity, and
| distinct from the adaptive immune responses associated with
| 'immune system memory'.
| Wowfunhappy wrote:
| My understanding was that breast milk (at least in humans) gave
| the baby antibodies, but not the ability to _create_ those
| antibodies. So, the effect wouldn 't last.
| [deleted]
| hutzlibu wrote:
| So it is even more frustrating, that mothers were encuraged for
| a long time, to not breast feed at all and rather use the
| artifical, sterile milk, because it is healthier. Fortunately
| the world moved largely beyond that.
| gerdesj wrote:
| How on earth could millions of years of evolution possibly
| compete with Nestle et al "science"? Did I only say millions?
| I meant: hundreds of millions, silly me.
|
| Perhaps evolution needs a better advertising budget.
| bisby wrote:
| That's like saying we'll never build a device that moves
| faster than we can run because evolution produced perfect
| locomotion for us. Or that we'll never be able to
| communicate further than we can yell, because evolution
| produced strong lungs for us.
|
| There are plenty of cases where evolution failed. Allergies
| for instance... our own immune system reacting quite
| imperfectly to a harmless substance. That doesn't sound
| like pinnacle of evolution perfection to me.
|
| There is a time that science wins and a time that natural
| things win. What if science added those antibodies to the
| formula? What about people who are unable to breast feed.
| tartoran wrote:
| When you're thinking that science won sometimes it's
| nothing else but a sponsored think-tank and a big
| marketing campaign that made you think so. Just saying.
| smallnamespace wrote:
| You may find the hygiene hypothesis interesting - the
| theory that the incredibly sharp rise in allergic
| diseases in developed countries is due to no longer being
| exposed to the types of bacteria that we had during most
| of evolution.
|
| One example is that allergy rates in Finnish Karelia are
| much higher than right across the border with Russia,
| even though the populations and environment are otherwise
| very similar.
| tartoran wrote:
| I get your joke, and it's not advertising but lobbying by
| the large corporations who make baby formula a recommended
| thing, eg sponsor a thinktank etc, and it's always 100%
| profit motive. Maybe we should get them off our backs and
| be aware that most of their products may be worse for us.
| And ideally change the mechanisms by which they are
| controlling the government. It's a tough fight because they
| are organized and have money and we aren't organized and
| our efforts need to be tenfold.
| acqq wrote:
| Thanks for sharing this, that got me reading:
|
| https://en.wikipedia.org/wiki/Colostrum
|
| and the article from 1961
|
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1359530/?page=1
|
| which quotes "first noted by Ehrlich in 1892" and "examined in
| detail by Howe in 1921."
| spacephysics wrote:
| Would epigenetics from past ancestors explain this? [0]
|
| [0] = https://www.scientificamerican.com/article/fearful-
| memories-...
| abainbridge wrote:
| No. The article says newborns don't have these activated CD4
| cells.
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(page generated 2020-04-22 23:00 UTC)