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Frank A. Bures: Macrophages maintain tattoos

April 8, 2018 GMT

Tattoos have been created to adorn a person’s skin for the past 5,000 years at best estimate. Many wish to keep them, but some folks find reasons to wish them gone. It has long been assumed that their well recognized persistence has been due to the remarkable range of substances used, including inks of various types and colors, being inserted into skin. These just lie there inert and undisturbed for each person’s forever mostly in dermal connective tissue fibroblast cells.

A very cleverly designed and executed study was published from France this March in the Journal of Experimental Medicine, which offers a much more dynamic explanation of their staying — and staying, and staying — power. It involves the pigments, synonymous with inks, being taken up by and into a kind of tissue fixed white blood cell called a macrophage (MACK-row fahj). The word’s roots are macro — for large, and phagein — eating. They’re part of our immune defenses. They confront and consume virtually anything foreign to their host like microbes and non-indigenous proteins, etc. The details and understanding of the entire process are too much to digest here.

Usually the macrophages ingest the undesirable debris and either metabolize it or send it packing into lymph nodes and vessels to end up in blood stream and be disposed of. Again, a gross oversimplification. The tattoo pigment granules they chow down are too big to munch up. They persist, internally maintained for what has been assumed an indefinite time.

Researchers in a French immunology lab engineered a strain of black mice to allow easy killing of their macrophages in some targeted manner. The initial studies observed that natural black pigment of the mice was absorbed inside macrophages after skin cells with it had died off. They then somehow killed the macrophage selectively, allowing the pigment to become free in dermis. They next found that new macrophages came into area and took up the pigment granules. To them it posed the question perhaps of a similar mechanism with tattoo pigments to maintain their presence.

They took their redesigned rodents and, without asking them what designs they might want, tattooed patches of green ink on their tales. The pigment was lodged in macrophages, as expected. Then their macrophages were subjected to cellular homicide. The green hunks were seen lying loose afterwards. But in 90 days new macrophages materialized and re-munched the green globs.

A second study phase was to remove a piece of greened tail and transplant it to recipient mouse’s back. The macrophages were done in. Low and behold, through a microscope naturally, loose pigment was found in different macrophages that belonged to the second critter, not the donor. It sort of proved that the response to the material was not host specific, one of those sticky scientific points (two puns here, sharp needles, eh?).

Many unrelated destructive approaches have been utilized over the centuries to eliminate tattoos without eliminating the bearer entirely. In our era a host of lasers have been developed to blast the pigment boulders apart into tinier gravel pieces that can be taken away via your lymph system. In some cases complete clearing without a scar can be achieved, but not always or often enough for those wishing their body art to vanish. It takes repeated sessions. Green can be a devilish color to clear by reputation. One newer laser is pretty good.

The theory behind the current study is that, if in some ingenious way your macrophages could be harmlessly sabotaged lethally to permit the pigment to be taken away, it could make removal easier, quicker, and more efficient. The new macrophages would not have time to rush into the fray and pick up the mantles and pieces from their fallen brethren.

Until then, the only truly total removal technique is to saw off hunks of skin, either in large swaths or bit by bit to lessen the ultimate scar. The only good thing about a surgical scar is it doesn’t tell a story, especially when ridding gang tattoos. Or Bob. How well I recall one young female patient who wore Bob on her bicep. But Bob became history in her life, and she wanted him gone from her body as well. We had to remove it in three segments for the smallest possible scar. As I made the final stroke with the scalpel on the last chunk to remove it, she said, “Bye, Bob.”