Scientists wondered (and didn't we all) why our body holds the pigment within the skin's layers to show off for a lifetime. Why not just take that foreign invader away to be processed like the trespasser that it is? How does this cell hold the ink after cell death? Well it turns out that the macrophages in our skin eat the ink and do eventually die. We don't know why. But we DO now know that when they die, the next microphage grabs the ink to hold in turn - and so on, until organism death!
(See the above picture of the microphage with wee ink bits inside).
Temporary inhibition of skin macrophage function is a therefore a possible way to disrupt this cycle and to remove a tattoo. With this approach, researcher and Immunologist Sandrine Henri of The French National Institute of Health and Medical Research says, “the pigment particle fragments generated by the laser pulses would not be immediately recaptured by macrophages—increasing the likelihood that they will drain away via the lymphatic vessels.” She and her team are on to the beginnings of easy tattoo removal.
Read more here:
https://www.sciencemag.org/news/2018/03/immune-cells-are-gobbling-your-tattoos-and-yet-still-keeping-them-place
https://www.scientificamerican.com/article/tats-off-targeting-the-immune-system-may-lead-to-better-tattoo-removal/