The researchers discovered that once a tattoo is made, the ink rapidly travels through the lymphatic system and, within hours, accumulates in large quantities in the lymph nodes — key organs of the body’s defense system. Inside these nodes, immune cells called macrophages actively capture all types of pigment. This ink uptake triggers an inflammatory response with two phases: an acute phase lasting about two days after tattooing, followed by a chronic phase that can persist for years. The chronic phase is particularly concerning because it weakens the immune system, potentially increasing the susceptibility to infections and cancer. The study also showed that macrophages cannot break down the ink like they would other pathogens, wich causes them to die, especially with red and black inks, suggesting these colors may be more toxic. As a result, ink remains trapped in the lymph nodes in a continuous cycle of capture and cell death, gradually affecting the immune system’s defensive capacity.
The study found that tattooed mice produced significantly lower levels of antibodies after vaccination. This effect is likely due to the impaired function of immune cells that remain associated with tattoo ink for long periods. Similarly, human immune cells previously exposed to ink also showed a weakened response to vaccination.
And yet, we manage to have hundreds of thousands of studies written about humans with human subjects. This sounds like a boatload of excuses that could be summed up as “science is hard”. Sure, it’s hard, but it’s better than putting out a flawed study that can’t scale properly.
You don’t need to sum it up as science is hard but also as science is expensive. They might simply not have gotten funding for something as that.
Sure, the study would be best if we did a randomised double blind study on a sample of 100 people that all are going to get a tattoo anyway but that doesn’t make the mouse study irrelevant.
Mice and humans, although very different in appearance have biomechanics that are very similar. For every human study you could make a 20 mouse studies with the same funding so you could do a lot more exploration.
This study found something, notably that ink in the blood affected the immune system. This just means that future studies are needed like injecting people with tattoo ink and blood samples diagnosis after tattoo to see how much ink is in the blood. If confirmed this will push tattoo ink manufacturers to develop a new ink that eliminates the effect and we can all enjoy safer more effective tattooing.
This study is not flawed, it’s pushing human knowledge forward like it always does.
It’s the size of the animal that’s important here. I’m aware that mice can sometimes have useful biomechanical similarities to humans, but this is the wrong animal to use in this case. Pigs would have been much much better.
Tattooing is a delicate operation that requires precision, even using different pressures between male and female human skin, and that does not scale well at all for an animal that is 100x smaller than a human.