上皮细胞并不属于免疫系统的一部分,可是在鼠类和人的皮肤中最普通的角质细胞,目前被认为可释放一种能刺激胸腺细胞和淋巴细胞增殖的物质,该激素样物质称为“上皮细胞衍生的胸腺细胞活化因子”(ETAF).ETAF除能增加一些淋巴细胞依赖性免疫活性如抗体产生外,还有一些非免疫方面的作用,如导致发热,帮助伤口愈合,并在许多慢性皮肤病的发病上起一定作用. Epithelial cells are not part of the immune system, but the most common keratinocytes in the murine and human skin are currently thought to release a substance that stimulates the proliferation of thymocytes and lymphocytes, called the hormone- “Epithelial cell-derived thymocyte activation factor” (ETAF). In addition to being able to increase some lymphocyte-dependent immune activities, such as antibody production, ETAF has some non-immune effects such as causing fever and helping wound healing, and at Many chronic skin diseases play a role in the pathogenesis.