Diaz-Araya C M, Madigan M C, Provis J M, Penfold P L
Department of Anatomy and Histology, University of Sydney, New South Wales, Australia.
Invest Ophthalmol Vis Sci. 1995 Mar;36(3):644-56.
To investigate the distribution and phenotype of major histocompatibility complex (MHC) class II-positive dendritic cells and macrophages in normal human fetal cornea in the age range 10 to 25 weeks gestation.
Peroxidase and gold immunohistochemistry were used to visualize MHC class II and macrophage antigen (S22) immunoreactive cells. Cell distributions were analyzed quantitatively, and topographic maps were produced.
Immunoreactive cells, concentrated centrally, were present at 10 weeks gestation in the corneal epithelium and stroma. Average densities increased steadily up to 25 weeks gestation. Two morphologic forms of MHC class II and S22 immunoreactive cells were observed--large, dendritiform cells and small, rounded cells with short processes. Electron microscopy revealed that most MHC class II-positive cells were morphologically consistent with previous ultrastructural descriptions of corneal Langerhans cells. Immunoreactive cells were more numerous in immunogold-labeled specimens than in peroxidase-labeled specimens of similar ages. However, quantitative analysis of both techniques revealed that S22-positive cells comprised 30% to 50% of MHC class II-positive cells.
This study provides a detailed description of heterogeneous populations of MHC class II and S22 immunoreactive cells in the human fetal cornea. In contrast to the adult cornea, which is typically devoid of MHC class II-positive cells, immunoreactive cells in the fetal cornea are concentrated centrally and increase in density up to at least 25 weeks gestation. These results indicate that reduction in Langerhans cell numbers to adult levels must occur after 25 weeks gestation. The presence of dendritic cells and macrophages in the fetal cornea has important implications for the understanding of corneal immunology.
研究妊娠10至25周的正常人类胎儿角膜中主要组织相容性复合体（MHC）II类阳性树突状细胞和巨噬细胞的分布及表型。
采用过氧化物酶和免疫金免疫组织化学法观察MHC II类和巨噬细胞抗原（S22）免疫反应性细胞。对细胞分布进行定量分析，并绘制地形图。
免疫反应性细胞集中于中央，在妊娠10周时存在于角膜上皮和基质中。平均密度在妊娠25周前稳步增加。观察到两种MHC II类和S22免疫反应性细胞的形态学形式——大的树突状细胞和带有短突起的小圆形细胞。电子显微镜显示，大多数MHC II类阳性细胞在形态上与先前角膜朗格汉斯细胞的超微结构描述一致。在相同年龄的免疫金标记标本中，免疫反应性细胞比过氧化物酶标记标本中的更多。然而，两种技术的定量分析均显示，S22阳性细胞占MHC II类阳性细胞的30%至50%。
本研究详细描述了人类胎儿角膜中MHC II类和S22免疫反应性细胞的异质性群体。与通常缺乏MHC II类阳性细胞的成人角膜不同，胎儿角膜中的免疫反应性细胞集中于中央，且密度在妊娠至少25周前增加。这些结果表明，朗格汉斯细胞数量减少至成人水平必定发生在妊娠25周之后。胎儿角膜中树突状细胞和巨噬细胞的存在对理解角膜免疫学具有重要意义。
