Author: Datetime:2017-04-19 Hits:
Unique immune cells, known as resident memory T cells, do an excellent job of preventing melanoma, scientists at Norris Cotton Cancer Center of Dartmouth University report in a newly published study. Their finding stems from an investigation of why patients with melanoma who develop the autoimmune disease called vitiligo have such good prognosis. Vitiligo is an autoimmune skin condition against normal healthy melanocytes, which causes the loss of skin pigmentation in blotches.
Using mouse models of melanoma and vitiligo, the research team found that resident memory T cells permanently reside in vitiligo-affected skin, where they kill melanoma cells. Although resident memory T cells were previously known to prevent skin viral infection, it was not known that they could fight tumors.
The research study, led by
Mary Jo Turk, Ph.D., sought to understand why patients with metastatic melanoma
who develop vitiligo during their course of treatment have been shown to
survive longer. Using a mouse model of vitiligo, Dr. Turk addressed why this
disease might be associated with a better clinical response. The study
demonstrates for the first time that resident memory T cells are generated in
response to a tumor, naturally as a result of autoimmune vitiligo, and serve a
critical role in protecting against future tumors. Their study, "Resident
Memory T Cells in the Skin Mediate Durable Immunity to Melanoma," appears
in Science Immunology.
This finding is surprising
because T cells that fight cancer have previously been thought to reside only
in immune organs such as spleen, lymph nodes, and blood and enter tumors from
the blood. "Our studies challenge this long-held belief by showing that
tumor-killing T cells already reside in skin, where they can rapidly respond
and kill melanoma cells" said Dr. Turk. Although these current studies are
limited to mice, the presence of similar cells might explain why human patients
with vitiligo are so well protected against melanoma and survive longer. Turk
and her team plan to look for these cells in human patients.