Tattoo ink alters immune cells and weakens some vaccine responses

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In a recent study published in PNAS, researchers investigated the journey of tattoo ink through the lymphatic system as it accumulates in lymph nodes and affects immune cells, examining its long-term effects on immune responses to vaccination.

They demonstrated that tattoo ink rapidly drains to lymph nodes, where macrophages take it up and often undergo cell death, triggering persistent inflammation for months. These effects were observed when vaccination occurred in the same lymphatic drainage area as the tattoo. Ink accumulation reduced immunity to messenger ribonucleic acid (mRNA) vaccines for the coronavirus disease 2019 (COVID-19) when administered at the tattoo site, but enhanced responses to an influenza vaccine in an ink- and timing-dependent manner.

The process introduces pigments deep into the dermis through repeated needle penetration. Because these pigments are designed to be insoluble and long-lasting, they often contain complex mixtures of binders, solvents, and industrial colorants.

While black tattoos typically use carbon black, colored inks commonly contain pigments originally designed for industrial applications such as plastics and paints. Despite widespread use, tattoo inks are far less regulated than pharmaceuticals or other substances intentionally introduced into the body. Although some toxicology data exist for individual ingredients, little is known about how inks behave inside living systems, especially over the long term.

Macrophages in the skin are known to engulf tattoo pigments, and tattoo-related pigment deposits have been reported in lymph nodes for decades. Mouse studies confirm that ink drains from the skin into lymph nodes, yet the immunological consequences of this process are poorly understood.

https://www.news-medical.net/news/20251127/Tattoo-ink-alters-immune-cells-and-weakens-some-vaccine-responses.aspx