What tattoos really do to our bodies' immune systems
Thu, 10/03/2019 - 8:37am
Source: CNN Health
Apia, SAMOA & Pago Pago, AMERICAN SAMOA — I lay on the mat of the open-air bungalow in Apia, Samoa, looking up at a gecko. As its tail quivered, I felt a sympathetic twitch in my leg. Su'a Sulu'ape Paulo III, the sixth-generation Samoan hand-tap tattoo master leaning over me, paused to see if my movement was due to pain.
I'd been in Samoa for a month, studying Samoan tattooing culture and the impact of the big traditional pieces called pe'a and malu -- tatau in general -- on the immune system. Now I was getting my own hand-tapped leg tattoo, albeit considerably smaller.
This field season was the fourth of my research on the relationship between tattooing and immune response. My first study had focused on a small sample, mostly women, in Alabama. What I'd observed among that group suggested that tattooing could help beef up one's immune response.
But one small study in the United States wasn't proof of anything -- despite headlines blaring that tattoos could cure the common cold. Good science means finding the same results multiple times and then interpreting them to understand something about the world.
That's why I traveled in 2018 with fellow anthropologist Michaela Howells to the Samoan Islands. Samoans have a long, continuous history of extensive tattooing. Working with contemporary machine and hand-tap tattooists in American Samoa, we wanted to see if we'd find the same link to enhanced immune response.
Immune defenders rush to tattoo's tiny wounds
More than 30% of Americans are tattooed today. Yet, few studies have focused on the biological impact beyond risks of cancer or infection.
Tattooing creates a permanent image by inserting ink into tiny punctures under the topmost layer of skin. Your body interprets a new tattoo as a wound and responds accordingly, in two general ways.
Innate immune responses involve general reactions to foreign material. So getting a new tattoo triggers your immune system to send white blood cells called macrophages to eat invaders and sacrifice themselves to protect against infection.
Your body also launches what immunologists call adaptive responses. Proteins in the blood will try to fight and disable specific invaders that they recognize as problems. There are several classes of these proteins -- called antibodies or immunoglobulins -- and they continue to circulate in the bloodstream, on the lookout lest that same invader is encountered again. They're at the ready to quickly launch an immune response the next time around.
This adaptive capacity of the immune system means that we could measure immunoglobulins in saliva as approximations of previous stress caused by tattooing.
In American Samoa, Howells and I worked at the Historic Preservation Office to recruit study participants with help from tattoo artists Joe Ioane of Off Da Rock Tattoos, Duffy Hudson of Tatau Manaia and traditional hand-tap tattooist Su'a Tupuola Uilisone Fitiao. Our sample of 25 tattoo recipients included both Samoans and tourists to the island.
We collected saliva at the start and end of each tattoo session, controlling for the tattoo duration. We also measured recipients' weight, height and fat density to account for health. From the saliva samples, we extracted the antibody immunoglobulin A, as well as the stress hormone cortisol and inflammatory marker C-reactive protein. Immunoglobulin A is considered a frontline immune defense and provides important protections against frequent pathogens like those of the common cold.
By comparing the levels of these biological markers, we determined that immunoglobulin A remains higher in the bloodstream even after tattoos heal. Furthermore, people with more time under the tattoo needle produced more salivary immunoglobulin A, suggesting an enhanced immune response to receiving a new tattoo compared to those with less or no tattoo experience. This effect appears to be dependent on receiving multiple tattoos, not just time passed since receiving one. This immune boost may be beneficial in the case of other skin injuries and for health in general.
Tattooing seems to exert a priming effect: That's what biologists call it when naive immune cells are exposed to their specific antigen and differentiate into antibodies that remain in the bloodstream for many years. Each tattoo prepares the body to respond to the next.
Other studies find that short-term stress benefits the immune system. Stress's bad rap comes from chronic forms that really do undermine immune response and health. But a little bit is actually good for you and prepares your body to fight off germs. Regular exercise provides immune function benefits through repetition, not necessarily single visits to the gym. We think this is similar to how each tattoo seems to prepare the body for vigilance.
Our Samoan findings supported the results of my first study in Alabama. But of course correlation does not imply causation. Enhanced immune response is correlated with more tattoo experience, but maybe healthier people heal easily from tattooing and like to get them more. How could we find out if getting tattoos could actually make a person healthier?