Overview
- Researchers at Humanitas University reported that pigments from common black, red and green inks migrated from tattooed skin to nearby lymph nodes and persisted for months.
- Macrophages that engulfed the pigment underwent cell death and the nodes showed sustained inflammatory signals in the mouse model.
- When vaccines were injected at tattooed sites, mice produced fewer antibodies after an mRNA COVID-19 shot, while responses to an inactivated influenza vaccine rose at early time points.
- The effects varied by pigment type, dose and injection location, and they were not observed when vaccination occurred away from the tattooed area.
- The peer‑reviewed study highlights regulatory and knowledge gaps around tattoo inks and calls for targeted toxicology and human studies to assess clinical relevance.