Mind & Body

Tattoos May Toughen Up Your Immune System

Sorry, Mom and Dad: Tattoos might actually be good for you. It turns out that going under the needle triggers a response that strengthens your immune system in the long run. While a single tattoo won't exactly cure the common cold, science shows that people with multiple tattoos have an enhanced immune response — at least, to new tattoos.

Immunity Is Skin Deep

Around 30 percent of Americans have at least one tattoo, but the research surrounding the possible health benefits of tattoos leaves a lot to be curious about. Most of the scientific studies of tattoos focus on what could go wrong, like melanoma and bacterial infection. But it's not all doom and gloom for those who get inked.

You can think of tattooing as an exercise for your immune cells. When you get a tattoo, the artist creates multiple tiny punctures in the top two layers of your skin — the epidermis and the dermis — with an ink-tipped needle. Those punctures lead to a force called capillary action that draws the ink deep down into your dermis. That triggers alarm bells for your immune system, which registers the ink as an intruder.

Your immune system rallies an army of white blood cells called macrophages to eat up the foreign ink cells. Normally, when macrophages arrive to chow down on an invader, it breaks that invader down and releases it as harmless waste. But tattoo pigment can't be broken down as easily as a virus or bacterium, so instead, the ink particles hang around inside the macrophages until they die and release their contents, which will just be consumed again by a new generation of immune warriors. In the meantime, a secondary line of defense called an adaptive response triggers the creation of specific immunoglobulin proteins that will circulate in the bloodstream to protect against the same types of invaders, just in case they return.

By detecting those immunoglobulins, scientists can measure the adaptive capacity of a person's immune system. That's exactly what they tried to do in a study looking at the effects of tattoos on the immune response. In 2016, Christopher Lynn and his colleagues tested people's saliva for immunoglobulin before and after tattoo sessions. They found that people who had more tattoo experience saw higher levels of immunoglobulin after the session, suggesting a stronger immune response for those with a greater number of tattoos.

Tit for Tat

Although Lynn's first study gave an inkling as to how tattoos affect the immune system, it wasn't a sure thing. The study only looked at a small sample of mostly women in Alabama. "Good science means finding the same results multiple times and then interpreting them to understand something about the world," Lynn writes for The Conversation. With that philosophy in mind, he set out for the Samoan Islands with anthropologist Michaela Howells.

Tattoos are an integral element of Samoan culture. For 3,000 years, the practice known as tatau has been an important coming-of-age ritual for men and women. The elaborate pe'a tattoo covers the male body from the mid-torso to the legs, and the female counterpart malu consists of a more minimal design on the thighs. With "people of all body types and walks of life" going under the needle for extensive tattooing, Samoans served as an ideal sample population for Lynn's second study.

Lynn collected saliva samples and health information from 25 participants, including some Samoans and some tourists to the island. In a pre-print study that has yet to be accepted to a peer-reviewed journal, he and his co-authors reported that tattooing seemed to cause a "priming effect" that prepared the body to respond to future tattoos. As in his previous study, people in this study with more tattoo experience produced more salivary immunoglobulin, which may also be beneficial for skin injuries and overall health.

While Lynn's findings in Samoa supported the results of his study in Alabama, more research needs to be done. He's continuing to collect saliva samples in Samoa to further investigate the immune response of people with extensive tattoos. For now, though, immunity may not be a good enough reason to go under the needle — there are plenty of other ways to strengthen your immune system, like sticking to a healthy diet and getting enough sleep.

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Love science and tattoos? Then you'll want to gaze upon the pages of "Science Ink: Tattoos of the Science Obsessed" by Carl Zimmer. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Andrea Michelson November 5, 2019

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