Reinhold U, Liu L, Sesterhenn J, Abken H
Department of Dermatology, University of Bonn, Germany.
Immunology. 1996 Nov;89(3):391-6. doi: 10.1046/j.1365-2567.1996.d01-744.x.
The absence of CD7 protein and the corresponding mRNA is a stable feature in a subset of normal circulating CD4+ memory T cells. It is still unresolved whether the CD7- subset represents a specific T-cell lineage. Here we show that repeated stimulation of highly purified CD4+ CD45RA+ CD45RO- naive T cells in vitro leads to the development of a distinct memory subset that is defined by the expression versus non-expression of the CD7 antigen. Comparing different T-cell activation pathways (TCR/CD3, CD2), we observed that alternative signals were critically involved in the development of CD4+ CD7- T cells. Peak mean numbers of CD7- memory cells occurred after 3-5 cycles of restimulation in vitro. Naive T cells that had undergone repeated stimulations were harvested and sorted into CD7+ and CD7- subsets. The vast majority (> 97%) of CD7+ T cells retained their expression, whereas the CD7- population did not re-express the antigen during further propagation of separated T-cell subsets. In CD7- cells no CD7 mRNA was monitored, indicating transcriptional regulation of CD7 expression. Certain differentiation-related antigens, including the cutaneous lymphocyte antigen CLA, were preferentially expressed on CD7- T cells. We suggest that absence of CD7 expression in a subset of CD4+ memory cells reflects a separate and stable differentiation state occurring late in the immune response. These T cells may represent the physiological counterpart of malignant T cells in certain forms of cutaneous T-cell lymphoma.
CD7蛋白及相应mRNA的缺失是正常循环CD4+记忆T细胞亚群中的一个稳定特征。CD7阴性亚群是否代表特定的T细胞谱系仍未明确。在此我们表明，体外反复刺激高度纯化的CD4+ CD45RA+ CD45RO-初始T细胞会导致一个独特记忆亚群的产生，该亚群由CD7抗原的表达与否来定义。比较不同的T细胞激活途径（TCR/CD3、CD2），我们观察到替代信号在CD4+ CD7-T细胞的发育中起关键作用。体外再刺激3-5个循环后，CD7记忆细胞的平均数量达到峰值。收集经过反复刺激的初始T细胞，并将其分选成CD7+和CD7-亚群。绝大多数（>97%）的CD7+ T细胞保持其表达，而在分离的T细胞亚群进一步增殖过程中，CD7阴性群体未重新表达该抗原。在CD7阴性细胞中未检测到CD7 mRNA，表明CD7表达受转录调控。某些与分化相关的抗原，包括皮肤淋巴细胞抗原CLA，在CD7阴性T细胞上优先表达。我们认为，CD4+记忆细胞亚群中CD7表达的缺失反映了免疫反应后期出现的一种独立且稳定的分化状态。这些T细胞可能代表某些形式皮肤T细胞淋巴瘤中恶性T细胞的生理对应物。
