Immune cells are like the Hatfields and McCoys of our bodies--once wronged, they never, ever forget. This is how we gain immunity, and it's why vaccines work: Immune cells develop a memory of an invading pathogen, and they build an alert system to find and fight it should it ever return. But a new study by Stanford researchers adds a new wrinkle to this long-held immune theory. It turns out immune cells can develop this memory-like state even for pathogens they've never met. This may come from exposure to harmless microbes -- or the memories may actually be borrowed from other, more experienced cells.
The findings could help explain why babies and small children are so susceptible to infectious diseases. They haven't been exposed to enough ever-present, mostly harmless pathogens yet, and it's the constant scuffle with these bugs that gives adult T cells a sort of cellular precognition. "It may even provide an evolutionary clue about why kids eat dirt," said the study's lead author, Stanford microbiologist and immunologist Mark Davis. Kids are drawn to dirt because they've got to expose their fledgling immune systems to something, to help build up their defenses.
Davis and his coauthors studied a group of T cells called CD4 cells, which are the same ones targeted by HIV. CD4 cells hang out in our bloodstreams and stand sentinel, sounding the cellular alarm when they spot something that doesn't belong. There are two basic classes of CD4 cells: Naive cells, which haven't been exposed to a particular bug and might take a while to mount a response, and memory-type cells, which have done battle with a pathogen and are on the lookout for it again. The memory cells can prompt action within a few hours, while naive cells might take days or even weeks--meanwhile, we're sick.
Decades ago, Davis discovered that CD4 cells reshuffle their DNA when they divide, which basically creates an army of T cells that have very specific pathogen-recognizing abilities. According to this new paper, this ability might also help them recognize pathogens they haven't even seen yet.
The researchers looked at blood samples from 26 healthy adults and figured out which T cells were responsive to which pathogens. About half of the cells looked like they were in the memory state, meaning they would have encountered a particular pathogen in the past. But then Davis and his colleagues did some tests and found out those people were never exposed to those diseases. They also tried this on newborns, using umbilical cord blood, and found the babies' cells were naive.
To test this further, the researchers took two adults who hadn't had a flu shot in five years and gave them the vaccine. After this dead-virus invasion, which is designed to give CD4 cells a new memory, the patients' CD4 memory cells proliferated. But interestingly, some of them were awakened to "remember" different bacterial and protozoan cell structures, which had nothing to do with the flu.
How do naive cells accomplish this microbial memory generation? It's all about the environment. People are constantly exposed to countless bacteria, fungi and viruses, everywhere all of the time. T cells might act like they're reacting to something they've seen before--maybe the bacteria's proteins look similar to that of a harmless bug, and the cell is fooled. Or maybe the actual memory cells reshuffle their DNA when they replicate, which gives new cells specific properties.
"The pre-existing immune memory of dangerous pathogens our immune systems have never seen before might stem from our constant exposure to ubiquitous, mostly harmless micro-organisms, in soil and food and on our skin, our doorknobs, our telephones and our iPod earbuds," Davis explains.
So maybe drop that Purell habit and don't worry about the billions of bugs, most of which aren't harmful, that surround us all the time. They might be giving our immune systems a head start.
The research appears this week in Immunity.
There are a lot of indicators that hyper-cleanliness during pregnancy may be causing the increase in allergies and auto-immune disorders. My mother is a nurse, so she was constantly washing her hands and using alcohol wipes and my brother, sister and I all have severe asthma, eczema and allergies, though neither of my parents or their siblings/parents do.
Time to get dirty, America.
I have believed for most of my life that you have to watch these "clean" ideas closely.
Yes it is important to wash your hands before you eat, but soap is enough. The same is true if are working around someone that is sick and spreading germs about.
But to try to live in a "pure clean" world is just not going to work, we did not evolve in that world and neither did the germs.
It has long been known that country kids exposes to far greater amounts of different germs when young have less allergies then the "modern city kid".
It is rare that we are born with immunity a give bug. We are born with the tools to become immune, but only if we play by the rules of nature, and are exposed to the "good guys", and even a few of the sort of bad guys.
But there is something people forget about life. Life will fill every spot possible.
If you look at any given surface it is full of life (germs, and such). If you destroy everything there, it will soon be replaced, but you do not get to pick what replaces what was there. On top of that say you use something that kills 99.9% of the germs. Sounds very impressive, but it means that you left 1 in 1000. And when you are dealing with millions if not billions of germs, you have in fact left quite a few. BUT what did you leave? The ones that are easy to kill? No! The ones that are hard to kill. Now think about the really nasty bugs, are they almost by definition hard to kill?
So what you just did is cleared out a big spot, left the hard to kill, and given the speed of reproduction of germs, you just gave the nasty germs a great head start.
People should really rethink the way the do things.
So the more you are exposed to certain bacterias will help you fight off others. Thats pretty interesting. It explains how babies and toddlers get sick easily, they aren't exposed to that many bacterias.
I don't know how this relates to any of this but... a few years ago my wife went on this purell kick. We had bottles of it in almost every room and she would 'order' my kids and I to use it regularly... or else!! Well we did for a good year or so. I stopped using it regularly after that first year and the kids too shortly after that stopped using it... regularly. Now my wife still carries a small bottle of it in her purse for the grocery store and places like that but, overall we hardly use it anymore. OK, now to my point.... my family as a whole was never sicker in our lives than those two or so years of heavy antibacterial use! Seemed like someone in the house always had a flu or a cold or a sinus infection or some other such illness.
I have another short tale to tell to help support this article... I have been a construction worker most of my life.. and there are many 'sayings' by the old timers in the business... such as when the dust and dirt is flying around and the young guys run for the masks... while the old guys take deep breaths and say, 'ah yeah.... sticks to your ribs, makes you strong!" Or when you cut yourself and they tell you to stick your bleeding finger in the wet concrete to seal the wound and disinfect it! Yeah sounds crazy.. but these old guys are never sick a day in their life. I would like to see a study of how many sick days non-union construction workers take as opposed to the general population. Cuz if youre not following osha standards, as a construction worker, you pretty much eat dirt and mold and so much crap every day.... Just sayin...
Today's magic is tomorrow's technology.
Nevertheless, GGenua, what are those 'old-timers' are most known for is their toughness. There's a of sickness they don't show. You can't see inside their bodies and they don't let you see everything going on inside their head, much like my 83 year old father.
From shipyards to heavy machine shops and smoking for 40 years, he's fought with emphysema since 1971, STILL refuses to use supplemental oxygen and is not bedridden. He's slowed down in the past few years but lives life on his terms - just like the 'old timers' you refer to.
Just because you don't 'see' it doesn't mean they ain't feeling it!
And as tough as you may be, you aint them. You didn't live their lives.
And PVC cement work great on cuts, too. Take it from an electrician. ;)
Octyl or n-butyl cyanoacrylates work better for sealing cuts and are readily available. I would recommend avoiding things with Cyclohexanone such as PVC cement as it can be toxic. Take it from a doctor ;)