Cigarette smoking has a long-term impact on the immune system, according to a new study.
Scientists from the French Institut Pasteur have found that years after smokers quit, the effects tobacco has on the body’s immune defence remain. The study was published in the scientific journal Nature on Wednesday.
The researchers set out to study what other factors, besides age, sex, and genetics, play a role in how the body defends itself against outside invaders.
They exposed blood samples from the 1,000 healthy individuals to viruses and bacteria and observed their immune responses, looking at 136 variables including body mass index (BMI), smoking, sleep, exercise, and others.
Three variables stood out: smoking, latent cytomegalovirus infection (an asymptomatic virus in the herpes family), and BMI.
Current smokers were found to have an increased inflammatory response when stimulated with bacteria, which was lost when they quit, the authors explained, but the smoking effects on T cell responses, the cells that help protect you from disease, continued years after quitting.
Long-term impact on immunity
“A comparison of immune responses in smokers and ex-smokers revealed that the inflammatory response returned to normal levels quickly after smoking cessation, while the impact on adaptive immunity persisted for 10 to 15 years,” Darragh Duffy, the head of the Translational Immunology Unit at the Institut Pasteur and last author of the study, said in a statement.
“This is the first time it has been possible to demonstrate the long-term influence of smoking on immune responses”.
The researchers said that it appears smoking leads to lasting changes to the immune system by affecting gene expression.
“This is a major discovery elucidating the impact of smoking on healthy individuals' immunity and also, by comparison, on the immunity of individuals suffering from various diseases,” said Violaine Saint-André, computational biologist at the Institut Pasteur and lead author of the study.
The scientists said further studies were needed on more diverse populations. More research could also help to identify the protein and gene interactions impacted by smoking.
“These findings provide new understanding on the effects of smoking on human health, and the role of modifiable environmental effects on immune response variability,” the authors concluded.