Co-parenting can make you closer in more ways than one.
Previous research on twins has indicated that environmental factors account for at least half of immune system diversity. Studies of vaccination response and resistance to infection have indicated that the adaptability of the immune system declines with age.
Researchers at VIB and KU Leuven in Belgium and the Babraham Institute in the UK looked in detail at the immune systems of 670 people, aged 2-86 years, over 3 years, to find out more about what causes diversity between individual immune systems.
The Belgian cohort consisted of 638 healthy volunteers aged 2-68 years, including 140, or 70 pairs, of co-parents of children.
In addition, 32 healthy English volunteers, aged 53-64 years of age, were involved, as part of an investigation into the impact of the winter 2014-2015 influenza vaccination.
Environmental factors cause immune systems to converge
The researchers observed that participants' immune systems would return to their original stability after temporary activity, reflecting the flexibility of the human immune system. They also found that age has a major impact on the immunological landscape.
One of the most potent factors that altered an individual's immune system was co-parenting a child. In individuals who lived together and shared a child, the variation between their immune systems was reduced by 50%, compared with levels of diversity in the wider population.
Medical News Today asked Prof. Adrian Liston, the researcher at VIB and KU Leuven who co-led the research, how long this would take. He said that more investigations would be needed to confirm this, but he speculated that it could happen quite fast, within months to a year.
One of the driving factors, he said, would probably be an exchange of gut microflora. He mentioned other research indicating that a 10-second kiss exchanges 80 million bacteria.
Prof. Liston added that the exchange of gut microflora would probably mean that a couple living together without children would also have similarities in their immune systems.
Parenting 'rewires the immune system'
Prof. Adrian Liston notes that parenting is "one of the most severe environmental challenges anyone willingly puts themselves through," and concludes that it is not surprising that it "radically rewires the immune system."
He adds, however:
"It was a surprise that having kids was a much more potent immune challenge than severe gastroenteritis. That's at least something for prospective parents to consider: the sleep deprivation, stress, chronic infections and all the other challenges of parenting does more to our body than just gives us grey hairs. I think that any parents of a nursery- or school-age child can appreciate the effect a child has on your immune system!"
Dr. Michelle Linterman, a researcher at the Babraham Institute who co-led the research, explains that individual immune systems vary due partly to genetics but also because of age. This, she says, probably explains why there is a declining response to vaccination and reduced resistance to infection as people get older.
Prof. Liston told MNT there would probably be similarities in immune traits between parents and children, too, although he added that genetic factors would also be at play, accounting for some 25% of the similarity, while age could increase the difference.
Apart from gut microbiota, the authors suggest that a shared environment, which normally includes socio-economic status, may also entail shared behaviors, such as smoking, diet, exercise and alcohol intake.
The results indicate that local conditions are a key factor in shaping the human immune system. Knowing this could help scientists determine health-related interventions, through clinical manipulation of environmental factors.
MNT recently reported that breast cancer chemotherapy can weaken the immune system for 9 months or longer.