A dose of dirt might be what the doctor ordered for a healthy immune system, new research has shown.
Stanford immunologist Mark Davis, who led the study which is published this week in the journal Immunity, compared the spectrum of immune cells contained in blood samples from adult donors and new-born babies.
Focusing on a subset of white cells called CD4 lymphocytes, which orchestrate the immune response by recognising pathogens and stimulating other cells to attack, Davis and his team found that, in the adults, there were CD4 cells capable of recognising all of the pathogens they tested.
Furthermore, up to 90% of the CD4 cells were memory cells; that is, quick-reacting cells that are made when an individual has met a particular threat previously.
The samples from the babies showed that they too had cells capable of recognising the pathogens, but, as one might expect, none of these cells were memory cells.
On it's own, this result doesn't sound surprising, until one realises that the adult donors had not actually ever been infected with some of the pathogens - such as HIV - being tested by the team.
So where were these memory cells coming from in the adults? "We don't know for sure," says Davis.
But he speculates that infections with low-virulence bugs trigger the immune system to develop also responses to other related bugs it hasn't seen before.
"We think this happens by about age ten," he says. "Now we need to work out how to prove it," because obtaining blood samples in this age group is tricky.
Davis likens the development of the immune system to the maturation of the brain.
"The brain needs to have input from the eyes for the visual system in order to see properly. The immune system's no different. It needs stimulating in childhood to make it develop properly."
Moreover, the findings might also explain why young children are much more vulnerable to infections that adults tend to brush aside. The difference, of course, being that, in adults, these immune memory responses discovered by Davis will have matured, so the adult immune response is far more robust and effective.
"Kids need to eat dirt!" says Davis, stirring his morning coffee, hopefully with a dirty spoon...
I personally believe we have got the whole bacterial thing scarily wrong and I hope its becoming obvious to the point of stopping the obsession with killing them all and being anti bacterial.
I've always had a problem with this idea, because I feel as though it encourages poor hygiene. Let's not beat about the bush here, the development of hygienic practices and sanitation over the past 100-200 years has been one of the top medical advancements of all time. The issue is that people take things into extremes -- living in an operating theatre is not great for your health, but neither is encouraging people to eat copious amounts of dirt in the name of immunity. Everything must be taken in moderation. Kids should be allowed to play outside and get dirty, but equally they should be made to wash their hands before meals and after going to the bathroom
I think you are right but only because people don't understand the difference between good and bad hygiene - mostly through scaremongering tactics of cleaning product advertisements. Its correct to say your baby's highchair table will have more bacteria than a toilet bowl but what they fail to say is it is totally different bacteria to those found in a toilet bowl and it is incorrect to state that ALL bacteria are bad for the sake of a few prevalent nasties (whose success is down to our own meddling in bacterial matters that we don't understand).
I've always believed that if a pacifier wasn't intended to get dirty, then kids would not drop them on the floor all the time!!! And, if kids weren't meant to put everything they can get their hands on into their mouths, they wouldn't do it.
Well-you cant worry about how every individual interprets the information they take in. Some will get it some wont-thats humans for you.... :)
I don't get too worried about germs within my own house.
No, you may not have explicitly stated it but you did imply it.
I haven't got much time but here are some links-I'm not sure if the last one will work but if you go onto the New Scientist website and enter bacteria cause speciation it will come up with about 10 relevant articles.
But could our cleanliness be the root cause of athsma and hay fever?
Look at how we immunise for viruses, a little of the thing that kills you, the body recognises and fights back with the cavalry immune system. It is easy to imagine the same scenario with bacteria, a little picked up here and there and body is strong to fight it for when a case of massive amounts are accidentally ingested. So for me, this highly suggests over-cleaning would weaken a persons resistance compared to a normal cleaning standard. With this sort of thinking , any bugs our immune system will fight may just increase the strength of the immune system that can carry over to fighting with new bugs etc. In my imagination there is wars going on and it seems bacteria can be made our ally - perhaps only as sparring partners for the immune system. Fight on little buddies! majorminor, Sun, 7th Apr 2013