Cell kinetic basis for pathophysiology of psoriasis.


Weinstein GD, McCullough JL, Ross PA J




Invest Dermatol


Studies on the cell proliferation kinetics of psoriatic epidermal cells are presented and the results compared to similar studies for normal epidermis. The short 36-h duration of the psoriatic cell cycle (Tc) is confirmed with the first double-peaked fraction of labeled mitoses (FLM) curve in human subjects. The growth fraction of psoriasis using two experimental techniques approximates 100% within 36 h, confirming the rapid Tc found by the FLM method. The cell kinetic basis for the pathophysiology of psoriasis consists of at least 3 proliferative abnormalities in comparison to normal epidermis. By far the largest alteration is the shortening of the Tc from 311 to 36 h. There is also a doubling of the proliferative cell population in psoriasis from 27,000 to 52,000 cells/mm and an increase in the growth fraction from 60% to 100%. As a consequence of these abnormalities the psoriatic epidermis produces 35,000 cells/day from a proliferative compartment of 52,000 cells/mm2 surface area. This is a 28-fold greater production of cells than the 1,246 cells/day produced in normal epidermis. The biochemical or control factors leading to these kinetic differences continue to remain elusive.