Paraskevas F, Lee S T, Orr K B
Immunol Commun. 1976;5(6):501-16. doi: 10.3109/08820137609033863.
Thymocytes exposed briefly in vitro to a variety of particulate substances (such as mycobacteria, erythrocytes of allogeneic cells) or to substances known to act in vivo as adjuvants (LPS or poly A:U), generate supernates which are able to induce cytophilic Ig in normal mouse serum in the presence of a foreign protein (antigen). This cytophilic Ig is taken up by 20-25% of splenic T cells. Hydrocortisone resistant thymocytes show the same property, while bone marrow cells are inactive. This activity is similar to that reported previously as being present in the 4S fraction of mouse serum, collected 6 hours after injection of complete Freund's adjuvant. It is proposed that this factor is responsible for the formation of complexes of Ig and antigen which have been detected in the serum 6 hours after immunization. Thymocytes collected 6 hours after priming in vivo with SRBC (when a subpopulation among them carries easily demonstrable surface Ig) are able to amplify markedly the antibody response particularly the 7S. It is postulated that the factor by generating the cytophilic Ig (complexes?) which is taken up by T cells, sets up a mechanism which markedly amplifies their helper cell function.
体外短暂暴露于多种颗粒物质（如分枝杆菌、同种异体细胞的红细胞）或已知在体内起佐剂作用的物质（脂多糖或聚腺苷酸:尿苷酸）的胸腺细胞，能产生上清液，在存在外来蛋白质（抗原）的情况下，该上清液能够在正常小鼠血清中诱导亲细胞性免疫球蛋白。这种亲细胞性免疫球蛋白被20% - 25%的脾T细胞摄取。氢化可的松抗性胸腺细胞表现出相同的特性，而骨髓细胞则无活性。这种活性类似于先前报道的在注射完全弗氏佐剂6小时后收集的小鼠血清4S组分中存在的活性。有人提出，该因子负责免疫后6小时在血清中检测到的免疫球蛋白与抗原复合物的形成。用绵羊红细胞在体内初次免疫6小时后收集的胸腺细胞（此时其中一个亚群带有易于证明的表面免疫球蛋白）能够显著增强抗体反应，尤其是7S抗体反应。据推测，该因子通过产生被T细胞摄取的亲细胞性免疫球蛋白（复合物？），建立了一种机制，显著增强它们的辅助细胞功能。
