Cell. 2015 Jan 15;160(1-2):37-47.
Variation in the human immune system is largely driven by non-heritable influences.
Brodin P, Jojic V, Gao T, Bhattacharya S, Angel CJ, Furman D, Shen-Orr S, Dekker CL, Swan GE, Butte AJ, Maecker HT, Davis MM.
There is considerable heterogeneity in immunological parameters between individuals, but its sources are largely unknown. To assess the relative contribution of heritable versus non-heritable factors, we have performed a systems-level analysis of 210 healthy twins between 8 and 82 years of age. We measured 204 different parameters, including cell population frequencies, cytokine responses, and serum proteins, and found that 77% of these are dominated (>50% of variance) and 58% almost completely determined (>80% of variance) by non-heritable influences. In addition, some of these parameters become more variable with age, suggesting the cumulative influence of environmental exposure. Similarly, the serological responses to seasonal influenza vaccination are also determined largely by non-heritable factors, likely due to repeated exposure to different strains. Lastly, in MZ twins discordant for cytomegalovirus infection, more than half of all parameters are affected. These results highlight the largely reactive and adaptive nature of the immune system in healthy individuals.
And, from the press release: “In a striking example of the immune system’s plasticity, the Stanford scientists found that the presence or absence of a single chronic, viral infection could have a massive effect on the system’s composition and responsiveness. Three out of five Americans and as many as nine out of 10 people in the developing world are chronic carriers of cytomegalovirus, which is dangerous in immune-compromised people but otherwise generally benign. In 16 of the 27 monozygotic twin pairs participating in the study, one member of the pair had been exposed to cytomegalovirus but the other had not. For nearly 60 percent of all the features Davis’ group measured, cytomegalovirus’ presence in one twin and absence in another made a big difference.” (Environment, not genes, plays starring role in human immune variation, study finds. By Bruce Goldman. Stanford School of Medicine News Center, Jan 15, 2015.)
Unfortunately, the full text won’t be available until 2016. This is important because anti-smokers, especially the Surgeon General, claim that smoking impairs smokers’ immune systems – while ignoring the fact that smokers are more likely to have been infected by CMV, for socioeconomic reasons. This is how they falsely blame smoking for diseases that are really caused by infection.