Effects of selective ultraviolet phototherapy (SUP) and local PUVA treatment on DNA synthesis in guinea pig skin.

The treatment with UV-light with wavelengths between 292.5--335 nm (known as selective UV-phototherapy, or SUP) and 320--390 nm (plus local treatment with 8-methoxypsoralen, known as PUVAex) gave rise to a biphasic reaction of epidermal cell proliferation in guinea pig skin. A decrease of proliferative activity was followed by a synchronized stimulation of DNA synthesizing cells after 2--4 h. These quantitative displacements were accompanied by qualitative changes in the proliferative behaviour of epidermal cells in the S-compartment.