Schiltz J R, Michel B, Papay R
J Invest Dermatol. 1979 Dec;73(6):575-81. doi: 10.1111/1523-1747.ep12541618.
These studies deal with the mechanism of pemphigus IgG-induced epidermal acantholysis. When normal human skin was culted with defined medium containing IgG from pemphigus serum, extensive epidermal acantholysis developed and heat-labile proteolytic enzyme(s) were recovered in the culture medium. The enzyme(s) displayed maximal activity at pH 6.5 when a 3H-amino acid-labeled, insoluble epidermal cell material was used as substrate. The enzyme activity increased during the first 3 days of culture and the appearance of maximal activity coincided with the time of onset of acantholysis. Acantholysis did not occur in control cultures incubated with normal IgG and the enzyme did not appear in the medium or in aqueous extracts of cultured tissues. The enzyme(s) is probably not of lysosomal origin because low pH-active proteases characteristic of these organelles remained within the cells. The effects of puromycin on appearance of enzyme activity, acantholysis and cell viability was studied. At cytotoxic concentrations, the appearance of the enzyme(s) and acantholysis were prevented, whereas at less toxic concentrations enzyme activity and acantholysis were not prevented. Because inhibition of protein synthetic rates by puromycin could not be dissociated from the cytotoxic effects, it is uncertain whether enzyme appearance and acantholysis were dependent upon living tissue or on specific protein synthesis. After pemphigus IgG was removed from the conditioned medium by DEAE cellulose and affinity column chromatography, the remaining material contained enzyme activity and caused acantholysis in fresh skin explants. Similar activities were not present in normal IgG-containing conditioned medium or unfractionated epidermal extracts from normal skin. These data indicate that when the pemphigus IgG autoantibody interacts with epidermal cell surface antigens, the cell responds by synthesis or activation of a non-IgG "pemphigus acantholysis factor" (PAF) which may be a nonlysosomal proteolytic enzyme. It is suggested that PAF causes loss of adhesion between keratinocytes and ultimately produces the characteristic acantholytic cells of pemphigus.
这些研究探讨了天疱疮IgG诱导表皮棘层松解的机制。当用人正常皮肤在含有天疱疮血清IgG的特定培养基中培养时，会出现广泛的表皮棘层松解，并且在培养基中可检测到热不稳定的蛋白水解酶。当使用3H-氨基酸标记的不溶性表皮细胞物质作为底物时，该酶在pH 6.5时显示出最大活性。酶活性在培养的前3天增加，最大活性的出现与棘层松解开始的时间一致。用正常IgG孵育的对照培养物中未发生棘层松解，且在培养基或培养组织的水提取物中未出现该酶。该酶可能并非源自溶酶体，因为这些细胞器特有的低pH活性蛋白酶仍保留在细胞内。研究了嘌呤霉素对酶活性、棘层松解和细胞活力的影响。在细胞毒性浓度下，酶的出现和棘层松解受到抑制，而在毒性较小的浓度下，酶活性和棘层松解未受到抑制。由于嘌呤霉素对蛋白质合成速率的抑制与细胞毒性作用无法区分，因此尚不确定酶的出现和棘层松解是依赖于活组织还是特定的蛋白质合成。通过DEAE纤维素和亲和柱色谱从天疱疮IgG的条件培养基中去除后，剩余物质仍具有酶活性，并能在新鲜皮肤外植体中引起棘层松解。含有正常IgG的条件培养基或正常皮肤的未分级表皮提取物中不存在类似活性。这些数据表明，当天疱疮IgG自身抗体与表皮细胞表面抗原相互作用时，细胞通过合成或激活一种非IgG的“天疱疮棘层松解因子”（PAF）作出反应，该因子可能是一种非溶酶体蛋白水解酶。有人认为，PAF导致角质形成细胞之间的黏附丧失，并最终产生天疱疮特征性的棘层松解细胞。
