Ichikawa Y, Shimizu H, Yoshida M, Arimori S
Fourth Department of Internal Medicine, Tokai University School of Medicine, Kanagawa, Japan.
Clin Immunol Immunopathol. 1992 Jan;62(1 Pt 1):91-6. doi: 10.1016/0090-1229(92)90027-l.
Phenotypic characteristics of lymphocyte components of the thymus were determined by two-color flow cytometry using monoclonal antibodies to T cell-differentiation antigens and activation antigens, and B cells in eight myasthenia gravis (MG) thymuses and eight thymomas including four associated with MG to clarify the roles of thymus in the diseases. Fifteen normal thymuses and four thymuses from non-MG patients were used as controls. Phenotypes of lymphoid components in thymoma resembled those in normal thymuses, in which the majority of lymphoid cells were immature (common) thymocytes (CD4+CD8+ or CD1+CD3-). The proportions of immature thymocytes, however, were relatively higher and those of mature thymocytes (CD4+CD8-, CD4-CD8+, CD1-CD3+ or CD2+CD3+) were lower in thymomas than normal thymuses. The results speculate that functions which support further differentiations of immature thymocytes into mature thymocytes are deficient in neoplastic epithelial cells of thymoma. In thymomas, therefore, occasional T cells might escape from the thymic surveillance system which eliminates auto-reactive T cells. Between thymomas associated with MG and those without, however, no significant difference was found in the proportions of thymocytes at various stages of maturation. In nonthymomatous thymuses from MG patients, an increase of both B cells (CD2-DR+ or CD2-CD21+) and activated T cells (CD2+DR+ or CD2+IL-2R+) was observed. Furthermore, immature thymocytes were significantly decreased and mature thymocytes were increased in the MG thymuses, as compared with normal thymuses, non-MG thymuses, and thymomas. These alterations were relevant to the histological findings observed in MG thymuses such as thymic involutions and germinal center formations: decreased immature thymocytes are considered to reflect thymic involutions, while germinal centers, in which lymphocytes from peripheral lymphoid organs are activated, are responsible for the increase of B cells, activated T cells, and mature T cells. In conclusions, our results suggest that neoplastic epithelial cells of thymomas are functionally deficient and that MG thymuses are immunologically active and resemble peripheral lymphoid organs.
采用针对T细胞分化抗原和活化抗原以及B细胞的单克隆抗体，通过双色流式细胞术测定了8例重症肌无力（MG）胸腺和8例胸腺瘤（包括4例与MG相关的胸腺瘤）中胸腺淋巴细胞成分的表型特征，以阐明胸腺在这些疾病中的作用。将15例正常胸腺和4例非MG患者的胸腺用作对照。胸腺瘤中淋巴细胞成分的表型与正常胸腺相似，其中大多数淋巴细胞是未成熟（普通）胸腺细胞（CD4 + CD8 +或CD1 + CD3 -）。然而，与正常胸腺相比，胸腺瘤中未成熟胸腺细胞的比例相对较高，而成熟胸腺细胞（CD4 + CD8 -、CD4 - CD8 +、CD1 - CD3 +或CD2 + CD3 +）的比例较低。结果推测，胸腺瘤的肿瘤上皮细胞缺乏支持未成熟胸腺细胞进一步分化为成熟胸腺细胞的功能。因此，在胸腺瘤中，偶尔会有T细胞逃脱消除自身反应性T细胞的胸腺监测系统。然而，在与MG相关的胸腺瘤和无MG的胸腺瘤之间，各个成熟阶段胸腺细胞的比例没有发现显著差异。在MG患者的非胸腺瘤性胸腺中，观察到B细胞（CD2 - DR +或CD2 - CD2 +）和活化T细胞（CD2 + DR +或CD2 + IL - 2R +）均增加。此外，与正常胸腺、非MG胸腺和胸腺瘤相比，MG胸腺中未成熟胸腺细胞显著减少，成熟胸腺细胞增加。这些改变与MG胸腺中观察到的组织学发现相关，如胸腺萎缩和生发中心形成：未成熟胸腺细胞减少被认为反映了胸腺萎缩，而生发中心（外周淋巴器官的淋巴细胞在此被激活）则导致B细胞、活化T细胞和成熟T细胞增加。总之，我们的结果表明胸腺瘤的肿瘤上皮细胞功能缺陷，而MG胸腺具有免疫活性，类似于外周淋巴器官。
