Smoking depletes your immunity for years after you quit

How does smoking affect the immune system? An analysis by J. Tsang and L. Luo at the Institut Pasteur (Paris Pasteur)

Cigarette smoke is a known health stressor, but the study of how it specifically impacts the immune system is relatively new, says John Tsang, a professor of systems immunology at Yale University. Yet the level of sway that smoking seems to have on the immune response roughly parallels that of age, sex, or genetics.

The health of your immune system is defined by how well it responds to things. The body prefers an immunity response that is not too large and not too small, but just right, so that it can fight infections and heal wounds, but not so much that it attacks itself.

The research group at theInstitut Pasteur is dedicated to studying how factors such as age, genetics and the environment affect immune responses. The 500 French men and 500 French women who donated blood for the study were asked a series of questions about their lifestyles.

The authors combined these results with information about 136 personal traits drawn from demographic, environmental and clinical data. cigarette smoking, body mass index and previous infections have strong associations with cytokine responses.

“This highlights the importance of considering not only the immediate effects, but also the enduring consequences of lifestyle choices on immune function,” says Yang Luo, a computational immunologist at the University of Oxford, UK, who was not involved in the research.

Smoking caused more inflammation than any of the other factors, and the data showed that it was as big an effect as sex, age, and genetics. After giving up cigarettes, the effects lingered for years. Saint-André and her team found that these factors correlated with patterns of chemical tags, called methyl groups, that were added to the cells’ DNA in certain regions. The addition of such methyl groups can alter gene activity.

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But the study still needs to be repeated to ensure that the results are generalizable, says Saint-André. In the future, it should have a more ethnic and racially diverse group of participants. She says the team is expanding their study to include participants from Hong Kong and Senegal. The researchers have also gone back to the original participants, and have collected fresh blood samples from 415 of them ten years after the original samples were taken.