Benoxaprofen photosensitization of phospholipase activation in mammalian cells in culture.

Benoxaprofen (BPF) induces a clinical photosensitivity which resembles idiopathic solar urticaria. This response is mediated by degranulation of mast cells. Since mast-cell degranulation is known to be modulated by phospholipid alteration, we examined the effect of BPF and ultraviolet radiation (UV) on phospholipid metabolism of C3H 10 T1/2 cells in culture. BPF + UVB (280-320 nm) induced release of [3H]arachidonic acid (AA) but did not alter the release of [3H]choline from prelabelled cells. This suggests that BPF photosensitizes phospholipase A2 activation. Such activation probably represents an integral step in the mechanism of BPF photosensitization of mast-cell degranulation.