Ultraviolet B induces mast cell apoptosis: a hypothetical mechanism of ultraviolet B treatment for uraemic pruritus.
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.
Szepietowski
J C
JC
Department of Dermatology and Venereology, University of Medicine, Wroclaw, Poland. jszepiet@derm.am.wroc.pl
Morita
A
A
Tsuji
T
T
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002460:Cell Line; D006801:Humans; D008407:Mast Cells / Q000473:pathology / Q000528:radiation effects*; D051379:Mice; D008954:Models, Biological; D011537:Pruritus / Q000209:etiology / Q000473:pathology / Q000532:radiotherapy*; D012867:Skin / Q000473:pathology / Q000528:radiation effects; D014467:Ultraviolet Therapy; D014511:Uremia / Q000150:complications / Q000532:radiotherapy*