Cytophotometric studies of epidermal proliferation in psoriatic and normal skin.

Cytophotometric measurements of single-cell DNA content were used to study human epidermal cell proliferation in vivo. It was found that Feulgen-DNA profiles can be used to assess proliferative activity in involved, uninvolved, and nonpsoriatic skin. Profiles of involved psoriatic skin were bimodal as is characteristic of actively proliferating populations. This was due to the presence of cells with twice (2C--presynthetic) or four times (4C--post-synthetic) the amount of DNA of the gametes, separated by the intermediate values of cells undergoing scheduled DNA synthesis. Profiles of uninvolved psoriatic as well as nonpsoriatic epidermis were unimodal with the majority of cells containing a 2C amount of DNA incating relatively low levels of proliferative activity. The observed variations in proliferative activity of these samples are discussed in terms of two alternative models. Since radioisotopes are not required, this technique presents a useful approach to studying human epidermal proliferation in vivo.