Where you live shapes your immune system more than your genes do

https://www.eurekalert.org/pub_releases/2016-10/cp-wyl100316.php

Public Release: 3-Oct-2016
Where you live shapes your immune system more than your genes
Cell Press

Like fingerprints, immune systems vary from person to person. And although we all inherit a unique set of genes that help us respond to infections, recent studies have found that our history and environment--like where and with whom we live--are responsible for 60% to 80% of the differences between individual immune systems, while genetics account for the rest.

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Long-term infections are responsible for most of the differences between individual immune systems. For example, when a person has herpes or shingles, the virus has more opportunities to interact with the immune system. These interactions slowly change the cellular makeup of their immune system and make it more sensitive to that specific virus but also easier for other infections to slip past its defenses. People without these infections don't experience these cellular changes, and even with the occasional cold or fever, their immune systems stay relatively stable over time.

The exception is when a person is elderly. Researchers haven't determined exactly why age plays a major role in making our individual immune systems more unique, but they have shown that aging changes how our immune system responds to threats. As we get older, an organ called the thymus gradually stops producing T cells, which are made to help to fight off infection. Without new T cells, older people are more likely to get sick and less likely to respond to vaccines.

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Differences can be overcome, however; studies of people living together have shown that air quality, food, stress levels, sleep patterns, and lifestyle choices had a strong combined effect on our immune responses. For example, couples who cohabitate have more similar immune systems compared to the general public.

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