Acid-Soluble Phosphates in Normal and Psoriatic Skin.

Abstract

ABNORMALITIES of phosphorus metabolism i M psoriaKis have been reported by many workers. Szakall and Weber (1959) found a considerable amount of inorganic phosphate and some organic phosphate in aqueous extracts of psoriatic scales, whereas only organic phosphate could he detected in normal stratum corneum. It was suggested that these findings might indicate a deficiency in phosphorylation mechanisms in psoriatie skin. In contrast, Braun-Falco and Salfold (I95i») reported an increase in organic phosphate in the water soluble component of psoriatic scales. Wheatley andFarber (1961, 1962) have confirmed this finding by showing the phosphorus content of psoriatic scale to be two-and-a-half times that of callus : most of this difference was due to an increase in organic phosphate. Findlay {1962} has shown that the phosphate composition of psoriatic scale is more akin to that of normal epidermis than that of plantar keratin.Mier and McCabe (1963) have measured the concentrations of acid-soluble phosphorus, phospholipid phosphorus, RNA phosphorus and DNA phosphorus in samples of normal and psoriatic skin. Their results, when expressed relative to the amount of DNA present, show that each fraction is increased in psoriasis. In a second paper (McCabe and Mier, 1963) these authors have shown that the increased amount of acid-soluble phosjihorus present in psoriatio skin can be accounted for almost entirely by an observed hicrease in the nucleotide content.A study of the phospholiiiids in psoriatie skin has been made by Gerstein (196:j). While ho found a raised concentration in involved skin, this difference disappeared when it was related to the DNA content of the skin. He was unable to detect a difference between the pattern of phospholipids found in psoriatic skin and normal skin. Whereas little or no change in the composition and content of pliospholipids in psoriatic skin has been demonstrated, the distribution of phospholipids in psoriatic skin has been shown to be grossly abnormal. The general histological picture (Braun-Falco, 195S ; Jarrett, Spearman and Hardy, 1959) is of phospholipids extending into the parakeratotic layer in contrast to normal skin where little phospholipid is found in callus (Wheatley and Farber, 1961). The interpretation of these facts supplied by Snider, Gottsehalk and Rothman (1949) is that phospholipids are broken down during normal keratinization, but that in the pathologically accelerated keratinization of psoriasis, this breakdown of phosphohpids is w * Pathological skin was obtained through the kind co-oporation of Dr. E. M. Donaldson, City General Hospital, Stoko-on-Trent and Dr. E. A. Fairburn, Unitod liirniingham Hospitals.