Korsrud F R, Brandtzaeg P
Scand J Immunol. 1981;13(3):271-80. doi: 10.1111/j.1365-3083.1981.tb00135.x.
Cytoplasmic J-chain expression by Ig-producing cells was characterized immunohistochemically in normal specimens of palatine and nasopharyngeal tonsils (adenoids). Altogether follicular immunocytes, which were mainly of ther IgG and IgM isotypes, showed a much higher percentage of J-chain positivity than the extrafollicular ones, in agreement with the idea that this polypeptide is principally a marker of differentiating or newly differentiated Ig-producing cells. Thus, in concurrence with the predominating IgG isotype, J-chain expression was almost 50% in the germinal centres of lymphoid follicles but only about 2% in the extrafollicular compartment. By contrast, a substantial number of J-chain-positive IgA immunocytes were found in the latter compartment. Since it is believed that extrafollicular Ig-producing cells are mainly derived from follicular centre cells, this result indicated that significant isotype switching is involved in tonsillar B-cell differentiation. Most tonsillar IgD immunocytes were J-chain-positive, in accordance with the notion that IgD expression is a feature of relatively early clonal development. It is postulated that J-chain-positive B-cell blasts may leave the tonsils and, through isotype switching, contribute to the dimer-producing IgA-cell populations normally found in the exocrine glands of the upper aero-digestive tract.
通过免疫组织化学方法，对腭扁桃体和鼻咽扁桃体（腺样体）的正常标本中产生免疫球蛋白（Ig）的细胞的细胞质J链表达进行了表征。总体而言，主要为IgG和IgM同种型的滤泡免疫细胞显示出比滤泡外免疫细胞更高的J链阳性百分比，这与该多肽主要是分化或新分化的产生Ig细胞的标志物这一观点一致。因此，与占主导地位的IgG同种型一致，J链表达在淋巴滤泡的生发中心中接近50%，但在滤泡外区域仅约2%。相比之下，在后一区域发现了大量J链阳性的IgA免疫细胞。由于人们认为滤泡外产生Ig的细胞主要来源于滤泡中心细胞，这一结果表明扁桃体B细胞分化涉及显著的同种型转换。大多数扁桃体IgD免疫细胞是J链阳性的，这与IgD表达是相对早期克隆发育特征的观点一致。据推测，J链阳性的B细胞母细胞可能离开扁桃体，并通过同种型转换，对通常在上呼吸道和消化道外分泌腺中发现的产生二聚体的IgA细胞群体做出贡献。
