Komatsu T, Yamamoto M, Shimokata K, Nagura H
First Department of Medicine, Nagoya University School of Medicine, Japan.
Virchows Arch A Pathol Anat Histopathol. 1989;415(1):79-90. doi: 10.1007/BF00718607.
Major histocompatibility complex (MHC) class II antigens are essential in the presentation of antigens to T lymphocytes, and cells expressing MHC class II antigens are known to play a role as antigen presenting cells (APC). We investigated the distribution of MHC class II antigens and the reactivity of monoclonal antibodies OKM1 and OKM5 in normal and fibrotic lungs immunohistochemically. The results showed that alveolar capillary endothelial cells (ACEnd) expressed MHC class II antigens and were reactive with OKM5 in both normal lungs and the non-thickened parts of alveolar septa of pulmonary fibrosis. However, ACEnd did not express MHC class II antigens and were not reactive with OKM5 in thickened alveolar septa of pulmonary fibrosis. Type II alveolar epithelial cells (AEp) proliferating and replacing type I AEp in pulmonary fibrosis expressed MHC class II antigens strongly. Alveolar macrophages expressed MHC class II antigens strongly and reacted with OKM1 in pulmonary fibrosis, especially in alveolar spaces. These findings suggest that the phenotypic changes of ACEnd may be involved in the process of pulmonary fibrosis, and type II AEp and alveolar macrophages in the parts of thickened alveolar septa may play a role as APC.
主要组织相容性复合体（MHC）II类抗原在将抗原呈递给T淋巴细胞的过程中至关重要，已知表达MHC II类抗原的细胞可作为抗原呈递细胞（APC）发挥作用。我们采用免疫组织化学方法研究了正常肺组织和纤维化肺组织中MHC II类抗原的分布以及单克隆抗体OKM1和OKM5的反应性。结果显示，在正常肺组织以及肺纤维化肺泡间隔未增厚部分，肺泡毛细血管内皮细胞（ACEnd）表达MHC II类抗原且与OKM5发生反应。然而，在肺纤维化增厚的肺泡间隔中，ACEnd不表达MHC II类抗原且与OKM5无反应。在肺纤维化中增殖并取代I型肺泡上皮细胞（AEp）的II型肺泡上皮细胞强烈表达MHC II类抗原。肺泡巨噬细胞强烈表达MHC II类抗原，且在肺纤维化中，尤其是在肺泡腔内，与OKM1发生反应。这些发现提示，ACEnd的表型变化可能参与了肺纤维化的过程，并且增厚肺泡间隔部位的II型AEp和肺泡巨噬细胞可能作为APC发挥作用。
