Vargas F, Tolosa E, Sospedra M, Catálfamo M, Lucas-Martín A, Obiols G, Pujol-Borrell R
Immunology Unit, Hospital Universitario Germans Trias i Pujol Universidad Autónoma de Barcelona, Badalona, Spain.
Clin Exp Immunol. 1994 Dec;98(3):478-88. doi: 10.1111/j.1365-2249.1994.tb05516.x.
NCAM (CD56) is a cell surface glycoprotein of the immunoglobulin superfamily expressed on neuroendocrine and natural killer (NK) cells which has considerable molecular heterogeneity due to differential splicing and post-translational modifications. NCAM has been detected in the thyroid follicular cells (thyrocytes) immunohistologically. We report here the molecular form, the modulation by cytokines and the levels of expression in thyroid pathology. By using a panel of MoAbs to NCAM on Western blots from thyrocyte extract we have determined that these cells express the 140- and 180-kD forms of NCAM. Exposure of primary cultures of thyrocytes to interferon-gamma (IFN-gamma), and even more, to the combination of IFN-gamma plus tumour necrosis factor-alpha (TNF-alpha) induced a clear increase in the expression of NCAM as assessed by FACS analysis. NCAM expression in thyrocytes was assessed by immunofluorescence in 59 surgical specimens of thyroid glands, and was found increased in 11/17 (64%) of Graves', in 5/25 (20%) of multinodular goitre (MNG) and in occasional adenoma glands. No correlation was found with the expression of HLA class I, class II or the degree of lymphocytic infiltration scored in adjacent sections, but it was often seen in areas infiltrated by macrophages. In conclusion, NCAM is an adhesion molecule whose expression is clearly increased in thyrocytes in autoimmune glands, probably as a consequence of exposure to cytokines locally released. Since one of the forms of NCAM expressed by thyrocytes has the capability to generate intracellular signal it may play a role in normal thyroid function. In addition, NCAM may facilitate the recognition of thyrocytes by lymphocytes, particularly by NK CD56+ lymphocytes.
神经细胞黏附分子（NCAM，即CD56）是免疫球蛋白超家族的一种细胞表面糖蛋白，在神经内分泌细胞和自然杀伤（NK）细胞上表达，由于剪接差异和翻译后修饰，其具有相当大的分子异质性。通过免疫组织化学方法已在甲状腺滤泡细胞（甲状腺细胞）中检测到NCAM。我们在此报告甲状腺病理学中NCAM的分子形式、细胞因子对其的调节作用以及表达水平。通过在甲状腺细胞提取物的蛋白质免疫印迹上使用一组针对NCAM的单克隆抗体，我们确定这些细胞表达140-kD和180-kD形式的NCAM。甲状腺细胞原代培养物暴露于γ干扰素（IFN-γ），甚至更明显地，暴露于IFN-γ加肿瘤坏死因子-α（TNF-α）的组合后，通过流式细胞术分析评估发现NCAM的表达明显增加。通过免疫荧光法在59个甲状腺手术标本中评估甲状腺细胞中NCAM的表达，发现在11/17（64%）的格雷夫斯病、5/25（20%）的多结节性甲状腺肿（MNG）以及偶尔的腺瘤性甲状腺中表达增加。未发现与相邻切片中I类、II类人类白细胞抗原（HLA）的表达或淋巴细胞浸润程度相关，但在巨噬细胞浸润区域常可见到。总之，NCAM是一种黏附分子，其在自身免疫性甲状腺中的甲状腺细胞表达明显增加，可能是局部释放的细胞因子作用的结果。由于甲状腺细胞表达的NCAM形式之一具有产生细胞内信号的能力，它可能在正常甲状腺功能中发挥作用。此外，NCAM可能促进淋巴细胞，特别是NK CD56 +淋巴细胞对甲状腺细胞的识别。
