Epidermal cell proliforation and differentiation in psoriatic skin

Cho, Kwang Hyun; Chang, Seung Ho; Kim, Young Gull; Youn, Jai Il; Park, Sang Chul; Ham, Eui Keun

Abstract

DNA replicating cells were detected in the psoriatic epidermis by anti BrdU antibody after incubating tissue sections biopsied in acute and chronic areas with BrdU. The expression pattern of No. 1 keratin, involucrin. filaggrin, loricrin and transglutaminase E was studied in the paraffin embedded sections of psoriatic specimen which showed various histopathological findings. The results are as follows 1) The labeling index of BrdU in lesional psoriatic skin was significantly greater than that in normal skin. The labeling index was greater in the clinically active lesion of psoriasis than that of the chronic lesion, which suggest that psoriatic lesions are composed of distinct lesions differing in activity. 2) In the epidermis of the psoriatic plaques with extensive parakeratosis or microabscesses at the base of the stratum corneum and absent granular layers, the expression pattern of five epidermal proteins appeared as follows : No. 1 keratin which is found in normal epidermis immediately above the basal layer, appeared several layers higher. Involucrin was detected in most of the suprabasal layers. Fillaggrin, loricrin and transglutaminase E showed negative expression. The results obtained in the present study suggest that the increment of DNA replicating cells and aberrant, maturation pathway of epidermis appear in active psoriatic plaques.