Scientists say that tattoos may cause local damage to the immune system

Information about the long-term consequences of tattooing on human health is still scarce, but the results of several new studies show that this art form can cause long-term inflammation in the body.

According to a research conducted on mice, tattoo ink accumulates in the lymph nodes and causes permanent changes in the body’s defense mechanisms by disrupting the immune system. In this study, mice that were tattooed showed chronic inflammation in their lymph nodes. These nodules were stained with ink particles and their antibody response to vaccines was also changed. Lymph nodes sampled from people with tattoos also showed similar signs of inflammation and discoloration, even years after the tattoo.

These results raise the possibility of a connection between tattoos and increased risk of diseases and indicate the need for more research. This point is raised by Santiago Gonzalez from the University of Lugano in Switzerland.

Referring to this issue, he says that during the tattooing process, the ink enters the body directly and the issue is not just an appearance change on the surface of the skin, but also results in the immune system. Gonzalez explains that long-term chronic inflammation can wear down the immune system, increasing the likelihood of infections or certain cancers. Therefore, there are many questions that need further investigation.

Tattoos have become a huge trend in recent years all over the world. Now between 30 and 40 percent of people in Europe and the United States have at least one tattoo. Although Gonzalez doesn’t have tattoos herself, she understands their artistic value and finds them aesthetically appealing. However, scientific information about the long-term effects of tattooing, especially its consequences on the immune system, is still limited.

Gonzalez says he and his colleagues became aware of the issue when, during a separate project on inflammation in mice, they observed that animals that had been shrunk to identify tattoos showed an unexpected and severe inflammatory response. This caused them to do more detailed investigations.

Using standard commercial inks in black, red, and green, the researchers tattooed a 25 mm square section of hind leg skin of several mice. With the help of advanced imaging equipment, they observed that the ink traveled through the lymphatic vessels quickly, in many cases within minutes, to nearby lymph nodes.

There, macrophages, which are among the most important immune cells for cleaning debris, pathogens, and dead cells, absorb ink particles and cause nodules to color and cause acute inflammation. About 24 hours later, these macrophages die and release the substance; Then other macrophages absorb it and the same cycle of death and ink absorption repeats many times. This process causes chronic and significant inflammation that continues long after the tattoo site has healed.

Gonzalez says that at the end of the experiment and two months after the tattooing, the levels of inflammatory markers in the lymph nodes of the tattooed mice were still up to five times higher than normal.

To investigate the effect of this inflammation on the function of the immune system, the researchers injected vaccines directly into the tattooed skin. The antibody response of the tattooed mice to the covid-19 mRNA vaccine was weaker than that of the control mice, but their response to the influenza vaccine became stronger.

Further investigation showed that the lymph node macrophages in the tattooed mice were so filled with ink that they absorbed less of the Covid-19 vaccine; A vaccine that requires processing by macrophages to be activated. On the other hand, the protein-based influenza vaccine caused a greater antibody response by increasing inflammation, which may be the reason for the increase in immune cells called to the tattoo site. Gonzalez says the immune response may depend on the type of vaccine.

Next, the researchers examined a limited set of lymph node biopsies in humans who had tattoos in areas close to the nodes. Even two years after the tattoo, the nodules still contained pigment particles and the macrophages in them showed the same pattern seen in the mice. According to Gonzalez, the lymph nodes of these people were completely filled with ink.

He added that the ink will likely remain in the lymph nodes for life, even if the person tries to remove the tattoo from the skin; Because it is possible to remove the ink from the skin, but it is not possible to remove it from the lymph nodes.

Christel Nielsen of Lund University in Sweden says the findings provide important insight into the possible link between tattoos and the immune system. Last month, he and his colleagues published a study reporting an increased risk of melanoma in people with tattoos. Nielsen explains that one of their hypotheses was the role of inflammation in the lymph nodes, and the results of this new study provide compelling evidence in support of this hypothesis. He considers this study an important step in understanding the relationship between tattoos and diseases.

Michael Giolbodaghian from the German Federal Institute for Risk Assessment in Berlin also believes that this research provides a more detailed picture of how tattoo pigments interact with the immune system. However, it emphasizes that the results obtained from mice are not necessarily fully generalizable to humans; Especially considering the significant differences between human and mouse skin. He says the importance of this issue for human health, especially after the wound has completely healed, needs more extensive investigations.