The effect of the proteolytic enzyme savinase on human plantar skin in vitro.

The effect of the proteolytic enzyme savinase on human plantar skin in vitro was examined by light and electron microscopy to elucidate the morphological involvement of activated savinase in human epidermis. Light microscopic examination of incubated skin fragments demonstrated that the histological changes produced by savinase in the epidermis, including the stratum corneum, depended upon pH value, enzyme concentration and incubation time. After incubation in 0.1% savinase in phosphate buffer, pH 8.0, for 2 h at 35 degrees C, the stratum corneum revealed a serrated appearance at the free edges, the viable cell layers showed acantholysis, particularly in the suprabasal area. Digestion of cytoplasmic components of horny cells was observed by electron microscopy, but both cell membranes and desmosomes remained intact. Detachment of basal and spinous cells was found in the viable epidermal cell layers. The main cytoplasmic changes consisted of the presence of numerous cytoplasmic processes and vesicular formations. The results of this study indicate that activated savinase digests the intercellular substance in the viable cell layers, but it does not digest horny cells without physical rupture of the cell membrane.