Overview
- A multi‑laboratory European team reported in PNAS that commercially common tattoo inks migrate through lymphatics to draining lymph nodes in mice and persist there.
- Pigments were retained in phagocytic cells, triggered macrophage death, and sustained a local inflammatory state observed for at least two months.
- When vaccines were administered at tattooed sites, antibody responses fell for an mRNA COVID vaccine but rose for an inactivated influenza vaccine, with no changes seen when injected away from tattoos.
- The magnitude and direction of effects depended on pigment color, dose, and location, with black and red inks producing more pronounced immune changes.
- Researchers used inks from a major supplier and emphasized that the results are from animal models, urging human studies and regulatory review of ink ingredients.