Long-term smoking affects immune system

Researchers at Institute Pasteur discovered that factors like age, sex, and genetics dramatically affect how our immune system responds to smoking. They studied 1,000 healthy volunteers to understand differences in immune responses. Smoking not only affects immunity in the short term but also has lasting effects. 

Even after quitting, ex-smokers still experience changes in their body’s defense mechanisms acquired during smoking. This study, published in Nature on February 14, 2024, is the first to reveal the long-term impact of smoking on immunity.

Researchers at the Institut Pasteur wanted to understand why people’s immune systems differ in how well they fight off infections. They studied 1,000 healthy individuals aged 20 to 70 to find out. Factors like age, sex, and genetics affect the immune system. However, they wanted to uncover other essential elements. 

They exposed blood samples from these individuals to different germs. They studied their immune response by measuring certain chemicals called cytokines. From the data collected, they found that smoking, latent cytomegalovirus infection, and body mass index significantly impacted immune responses, similar to age, sex, and genetics.

The study found that smoking affects the body’s response to infections in two different ways. First, it increases inflammation when infected. Second, it weakens specific cells involved in remembering how to fight off infections in the future. This means smoking disrupts both immediate and long-term immune functions.

Comparing smokers to ex-smokers, researchers found that inflammation returned to normal shortly after quitting. However, the effects on long-term immune memory lasted for 10 to 15 years. This study is the first to show the lasting impact of smoking on immune responses.

The immune system remembers the effects of smoking for a long time, similar to a memory. Researchers suspected that epigenetic processes, which can change how genes work without altering the DNA sequence, were involved. 

They found that differences in DNA methylation, a type of epigenetic change, were linked to the long-term effects of smoking on immune responses. This means smoking can cause lasting changes to the immune system through epigenetics.

This discovery is essential for understanding how smoking affects both healthy individuals’ immunity and those with various diseases.

This study demonstrates that smoking has significant long-term effects on the immune system. It highlights the inflammatory response to pathogens and impairs immune memory, leading to persistent alterations in immune function. 

Journal reference:

1. Saint-André, V., Charbit, B., Biton, A. et al. Smoking changes adaptive immunity with persistent effects. Nature. DOI: 10.1038/s41586-023-06968-8.