Vitiligo and non-self

Donald Forsdyke forsdyke at
Fri Mar 5 22:54:15 EST 2004

In organisms inwhich melanomas are being attacked by host T-lymphocytes,
patches of pale skin sometimes appear ("vitiligo"). It seems that the
T-lymphocytes are attacking not only the melanoma cells, but also the
relatively uniformly distributed melanin-producing cells in the skin. This
is consistent with the idea that normal self antigens (not specific tumor
antigens) are the usual targets of cytotoxic T-lymphocytes.

     One explanation of vitiligo would be that specific host T-lymphocytes
are at a very low concentration and the patches appear where a specific
T-lymphocyte happens to encounter an appropriate antigen on a skin cell.
However, a recent paper in Cancer Research by Lane et al. (February 15)
presents evidence that the vitiligo is secondary to trauma. Thus, there may
be an abundance of T-lymphocytes of a sufficient degree of specificity, but
they only attack when some "not-self" (i.e. external) agent has inflicted
trauma on the skin. Thus, the first event is triggering by not-self. This
would provoke the upregulation of MHC-protein production and the
presentation of peptides for T-cell recognition.

Donald Forsdyke. Discussion Leader. Bionet.immunology

This message was sent to Bionet.immunology, but the newsgroup "could not be
resolved" so it is being sent to the other group for which I am Discussion
Leader, Bionet.journals.note. Hopefully, someone in the Bionet
administration will "upregulate" Bionet.immunology so that it can be
resolved in future.

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