Change makes us uncomfortable. As people who live in a dynamic world, we tend to derive comfort from the constants in our lives: the morning coffee we drink everyday, the social media we check every morning, the class schedule we follow all semester. What we fail to realize, however, is that each of these aspects of our lives is not as permanent as we might think. Tastes change, social media loses its charm, and schedules grow mundane. We feel comfortable living our lives with an “illusion of constancy” that keeps us neatly sheltered within our comfort zone, safe from the perils of the unknown. We apply this same “illusion of constancy” to tattoos; we think of them as fixed embellishments that lay neatly sandwiched between layers of connective tissue and epithelium, forming a fixed image that will remain under our skin for a lifetime. Seeing past the illusion, we come to realize that tattoos are part of a dynamic response involving the mingling of macrophages and the hurry of histamines rushing to the site of the inflammation caused by the tattoo needle.
Though it seems innately counterintuitive for a defensive immune response to promote the persistence of tattoos, the science underlying tattoos paints a clearer picture of how the process works. It was originally believed that tattoo pigments simply stained fibroblasts, the fixed cells in our skin that produce collagen, but a recent study testing other aspects of the immune system completely overturns this notion.
Recently in the Journal of Experimental Medicine, there was a study published regarding the macrophage dynamics that underlie both the persistence and the removal of tattoos, and this study has undoubtedly shed light on a topic that gets under many peoples’ skin ( literally).
In their model of tattoo persistence, French scientists discovered that macrophages—immune cells responsible for ingesting foreign particles or debris—play a crucial role in giving tattoos the illusion of stasis on skin. According to Bruce Klitzman, a researcher at Duke University working on creating an erasable tattoo, “Macrophages can basically swallow many, many tattoo pigment particles, almost like a vacuum cleaner,[they] just go along and suck up all those molecular interlopers.”
The researchers began their investigation, by giving a group of genetically engineered lab mice tattoos. Though the mice did not have the privilege of donning a cheesy quote or an angsty symbol of teenage rebellion across their tiny chests, they did get 3 bands of green ink tattooed upon their tails, and these bands served as excellent models of how the immune response prolonged tattoo viability in the dermis.
According to immunologists involved in the study, “mouse skin can be super fragile, much more fragile than human skin,”and this attests to the immense viability of using mice as a model for the human immune response to tattoos.
Each of the mice used in the study were genetically engineered to enable the researchers to manipulate various aspects of their immune systems. For instance, researchers removed the macrophages present in the dermis of a sample of mice and observed the effects on the tattoos as healthy macrophages were killed and then regenerated by precursor cells called monocytes. To their surprise, the shape of the tattoos remained unchanged as the macrophages went through this continuous cycle of cell death and regeneration, constantly sucking up ink particles and releasing them upon death.
On a cellular scale, the ongoing process of pigment “capture, release, and recapture,” as the researchers call it, is the driving force behind tattoo retention in the dermis. Dermal macrophages initially capture the pigment from the tattoo ink, and our tattoo pigments shine through their transparent cells to give us the illusion of permanent body art. As the macrophages age and eventually die, the ink globules are released extracellularly into layers of connective tissue beneath the skin.
So what are the implications of this research for tattoo removal? Can we simply erase the tattoos from the stained fibroblast cells? Or is a macrophage mass removal in order? It seems that like most things, the answer is far more complex than we initially anticipated.
Statistically speaking, about 1 in 5 adults have at least one tattoo, and there are over ten thousand laser tattoo removals performed globally. Researchers from this study believe that targeting macrophages in the tattoo removal process can lessen the average amount of treatments for removal from 20 treatments to a mere 10, as evidenced by treatment proposals from dermatologists across the US.
Dr. Jared Jadego, one such dermatologist from U.C. Davis, conducted laser tattoo removal procedures using an anti-inflammatory ointment that suppressed macrophage activity in the dermis. Using this method as opposed to the standard laser tattoo removal, he was able to remove over 90% of the tattoo in half the amount of treatments as the standard procedure. Though these studies are still in their primitive stages, they show great promise for the future of tattoo removal.
In life, our perception of reality is weighted heavily by what we believe to be true, so in science we must venture beyond the bounds of our comfort zone to unapologetically pursue the truth, even though it may challenge preconceived notions that once appeared constant. For now, it seems that tattoos retain their permanence, but in light of the science underlying the popular body art, they are by no means the static, unchanging art forms that we once thought them to be.