Author(s): Szepietowski JC, Morita A, Tsuji T
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Abstract The pathogenesis of uraemic pruritus is unclear, although there is some evidence that an increased number of skin-infiltrating mast cells may play a role. Ultraviolet B reduces itchy sensation of uraemic patients by leading to depletion of cutaneous mast cells. This study presents data that both broad-band and narrow-band ultraviolet B irradiation are able to induce apoptosis in transformed mast cells (murine mastocytoma cell line P815) in a dose-dependent manner at a time point of 24 hours. The positive apoptotic rates were as follows: sham-exposed cells (controls) -- 13.3\% +/- 0.6\%; with broad-band ultraviolet B irradiation -24.5\% +/- 1.1\% with 10mJ/cm(2), 57.9\% +/- 4.6\% with 20mJ/cm(2) and 70.9\% +/- 4.5\% with 30mJ/cm(2); with narrow-band ultraviolet B irradiation -- 29.6\% +/- 2.3\% with 100mJ/cm(2), 57.3\% +/- 4.1\% with 200mJ/cm(2) and 81.5\% +/- 1.9\% with 300mJ/cm(2). The difference between the number of apoptotic cells in all groups of ultraviolet B-irradiated cells and sham-exposed cells was highly significant (P<0.001). Based on these findings, it is hypothesized that ultraviolet B induced mast cell apoptosis could be an important factor in phototherapy for the diseases dependent on increased number of cutaneous mast cells, including uraemic pruritus. Copyright 2002 Harcourt Publishers Ltd.
This article was published in Med Hypotheses
and referenced in General Medicine: Open Access