Aiba S, Tagami H
J Invest Dermatol. 1986 Feb;86(2):121-4. doi: 10.1111/1523-1747.ep12284113.
Ia antigen-bearing (Ia+) Langerhans cells have attained an important position as immunocompetent cells in the epidermis. Recently there have been successive reports on other new possible candidates for immunocompetent cells in the epidermis, i.e., Ia+ keratinocytes and dendritic Thy-1 antigen-bearing (Thy-1+) epidermal cells which also express Ly-5 antigen and asialo-GM1. Based on our previous findings that in allergic contact sensitivity reactions, keratinocytes express Ia antigen 3-9 days postchallenge, in this report, we have attempted to define more clearly the dynamic changes of Ia+ keratinocytes and dendritic Thy-1+ epidermal cells by enumeration of the precise percentages of Ia+, Thy-1+, and Ly-5 antigen-bearing (Ly-5+) cells in epidermal cells at various times of the challenge phase in allergic contact sensitivity reactions by use of a fluorescence-activated cell sorter. By 24 h postchallenge, the percentages of Ia+, Thy-1+, and Ly-5+ cells showed hardly any change. There were approximately 2% Ia+ cells, 50% Thy-1+ cells which consist of 2 populations (i.e., 45% weakly Thy-1 antigen-positive cells and 4% strongly Thy-1 antigen-positive cells), and 3.5% Ly-5+ cells. From 48 h postchallenge, however, the percentage of Ia+ cells and that of Thy-1+ cells began to increase and reached a plateau, with approximately 20% Ia+ cells and 70% Thy-1+ cells, respectively, at 120 h postchallenge. The change of the percentages of Ly-5+ cells appears to correspond to that of strongly Thy-1 antigen-positive cells. Only at 48 h postchallenge, Ly-5+ cells and strongly Thy-1 antigen-positive cells showed a small increase in number, comprising approximately 10% of the epidermal cells. These data suggest that among Thy-1+ epidermal cells, strongly Thy-1 antigen-positive cells correspond to dendritic Thy-1+ epidermal cells, and in contact sensitivity reactions in mice, dendritic Thy-1+ epidermal cells show only a minor dynamic change in contrast to Ia+ cells, in which more than 15% of keratinocytes express Ia antigen from 48 h postchallenge.
携带Ia抗原（Ia+）的朗格汉斯细胞已在表皮中作为免疫活性细胞占据重要地位。最近，陆续有报道称表皮中免疫活性细胞可能有其他新的候选者，即Ia+角质形成细胞和携带树突状Thy-1抗原（Thy-1+）的表皮细胞，后者也表达Ly-5抗原和去唾液酸GM1。基于我们之前的发现，即在过敏性接触敏感性反应中，角质形成细胞在激发后3至9天表达Ia抗原，在本报告中，我们试图通过使用荧光激活细胞分选仪精确计数过敏性接触敏感性反应激发阶段不同时间表皮细胞中Ia+、Thy-1+和携带Ly-5抗原（Ly-5+）细胞的精确百分比，来更清楚地界定Ia+角质形成细胞和树突状Thy-1+表皮细胞的动态变化。激发后24小时，Ia+、Thy-1+和Ly-5+细胞的百分比几乎没有变化。大约有2%的Ia+细胞、50%的Thy-1+细胞（由两个群体组成，即45%的弱Thy-1抗原阳性细胞和4%的强Thy-1抗原阳性细胞）以及3.5%的Ly-5+细胞。然而，从激发后48小时开始，Ia+细胞和Thy-1+细胞的百分比开始增加并达到平台期，在激发后120小时分别约为20%的Ia+细胞和70%的Thy-1+细胞。Ly-5+细胞百分比的变化似乎与强Thy-1抗原阳性细胞的变化相对应。仅在激发后48小时，Ly-5+细胞和强Thy-1抗原阳性细胞数量略有增加，约占表皮细胞的10%。这些数据表明，在Thy-1+表皮细胞中，强Thy-1抗原阳性细胞对应于树突状Thy-1+表皮细胞，并且在小鼠的接触敏感性反应中，与Ia+细胞相比，树突状Thy-1+表皮细胞仅表现出微小的动态变化，其中超过15%的角质形成细胞在激发后48小时开始表达Ia抗原。
