On average, we each shed roughly 30,000 to 40,000 skin cells per hour. If we’re losing all of that skin all of the time, why do tattoos stay in place? The answer: Tattoo ink resides not in skin cells but as part of the immune system. White blood cells, known as macrophages, arrive at the tattoo site to repair a newly tattooed injury, seeking to remove the foreign body (tattoo ink).
Macrophages can’t break down this ink, so they “eat” it and remain in place to protect the skin. When those macrophages die, other macrophages arrive to consume the released ink. That’s why removing tattoos is extremely difficult. While lasers can kill the cells and ink-holding macrophages, more macrophages arrive to repair the skin injury caused by the laser. They consume the ink released by the macrophages killed in the tattoo removal process, which is why a tattoo often looks faded after a few removal sessions.