Tattoos can cause lifelong changes to the body’s immunity as well as affect vaccine responses, according to a new study.
An international team of researchers has found that tattoo ink collects in the lymph nodes, affecting the body’s resistance to disease, in findings published in the Proceedings of the National Academy of Sciences.
While studies have previously investigated the toxicity of tattoo ink, scientists say this is the first time their effect on immune responses has been explored.
Using tattoos on mice, researchers found that the animals demonstrated chronic inflammation in their lymph nodes that was “acute and long-lasting”, the death of macrophages (a type of white blood cell), and altered immune response to vaccinations.
“This work represents the most extensive study to date regarding the effect of tattoo ink on the immune response and raises serious health concerns associated with the tattooing practice,” the team said, noting that at least one in five people have a tattoo globally.
“Our work underscores the need for further research to inform public health policies and regulatory frameworks regarding the safety of tattoo inks.”
Scientists were first intrigued when they noticed that mice which had been tattooed for other experiments exhibited inflammation and decided to investigate further.
They used standard commercial inks in black, red and green to tattoo the skin on the hind feet of mice. Using specialised imaging equipment, scientists noticed the ink travelled along the lymphatic vessels to nearby lymph nodes, often within minutes, where it accumulated.
Researchers also noted that the ink appeared to affect vaccination response with a reduced response to the Covid-19 vaccine and an enhanced response to the UV-inactivated influenza vaccine, “reflecting differences in the mechanisms of action between these vaccine classes”.
“One of the urgent concerns associated with the safety of tattoos regards the potential redistribution of the unretained ink from the tattoo site to organs other than the skin and the toxic effect that the accumulation of these insoluble pigments might have at systemic levels,” the researchers concluded in their report.
Importantly, the ink is reported to stay in the lymph nodes for a lifetime, even if the tattoo is removed.
“Considering the unstoppable trend of tattooing in the population, our results are crucial in informing the toxicology programs, policymakers, and the general public regarding the potential risk of the tattooing practice associated with an altered immune response,” the authors of the study wrote.
Extensive recent research has linked tattoos to a type of cancer called lymphoma. A study published in BMC Public Health found that the risk of lymphomas could be three times higher for people with large tattoos compared to those without.