When any antigen breaches the skin barrier, the local immunologic response
includes cell-mediated translocation of the antigen to the local lymph nodes
from where a systemic immune response is initiated. The translocation of tattoo
ink seems to be very effective; it has been estimated that 32% of the injected
pigment is translocated after 6 weeks, and that as much as 99% may become
translocated over time.
In clinical settings, pigmented and enlarged lymph nodes have been described in
tattooed individuals for decades. Translocation of both black and coloured
tattoo pigments to human lymph nodes has been confirmed, as have depositions of
metal particles from tattoo needle wear.
That is - it's not just during the healing period, and that it's been confirmed rather than a hypothesis.
