How smoking damages the immune system in the long term
Lung cancer, cardiovascular diseases, COPD: the list of health consequences of smoking is long and serious. The susceptibility to infections also increases – especially respiratory diseases. Smokers are not only more likely to become infected with a cold or flu, but the illnesses are also often more severe.
During the corona pandemic it quickly became apparent that smoking was a significant risk factor for serious illnesses. The reason: Smoking weakens the immune system, especially in the nose, bronchi and lungs .
Only the innate immune system recovers quickly
A study by the Institute Pasteur confirms that those who give up smoking have their immune system recover quickly. But this apparently only applies to the innate immune system. This forms the first bulwark against pathogens and attacks all foreign intruders.
The acquired immune competence, which stores information about pathogens that have already been successfully combated and can therefore react quickly and specifically in the event of renewed contact, remains “low speed” even years after quitting smoking.
Immune reaction tested in blood
The French research team exposed blood samples from 1,000 healthy people between the ages of 20 and 70 to a variety of pathogens. They then determined the immune response based on the cytokines that the immune cells released. These are inflammatory messengers that summon additional immune cells to eliminate pathogens such as bacteria and viruses.
The researchers then determined which of the 136 disease-promoting factors examined had the strongest influence on the immune response. In addition to current and previous smoking behaviour, this also included variables such as body mass index, number of hours of sleep, exercise, childhood illnesses, vaccinations and living environment.
Long-term effects of smoking, BMI, Pfeiffer’s glandular fever
Three factors particularly stood out: smoking, a higher body mass index and a latent infection with the cytomegalovirus, the pathogen that causes Pfeiffer’s glandular fever. “The influence of these three factors on certain immune reactions appears to be as serious as age, gender and genetic predisposition,” explains study leader Darragh Duffy.
What was new was the finding that the activity of certain cells involved in immune memory was impaired. “Comparing the immune responses of smokers and ex-smokers showed that the immediate inflammatory response quickly returned to normal levels after quitting smoking, while the effects on adaptive immunity lasted for 10 to 15 years,” said Duffy. The study was the first to show an effect of smoking on the long-term memory of the immune system.
Epigenetic changes weaken the immune response
The team was also able to find the cause of the persistent effects on immune memory: smoking causes so-called epigenetic changes in the genome. It is not the genetic code itself that is changed, but certain “switches” that decide which genes are read and which are not. Small building blocks, so-called methyl groups, which attach themselves to the genetic code, act as switches. Compared to people who had never smoked, the epigenetic patterns that are involved in the metabolism of immune cells were noticeably changed in smokers and ex-smokers.
It’s never too late to stop
Here in the UAE the designated smoking areas at work remain ever popular as do the growing number of shisha cafes. Despite all the warnings and deaths caused by smoking people continue to indulge in this bad habit, perhaps comforted by some notions that “it won’t be me”, “I’ll stop soon before something terrible happens”, etc. People’s immunity being damaged with immediate and sometimes irreversible consequences, is just one more reason to kick the habit.