Thymocyte stimulation by anti-TCR-�, but not by anti-TCR-�, leads to induction of developmental transcription program

Abstract: Anti-T cell receptor (aTCR) antibody (Ab) stimulation of T cells results in TCR down-modulation and T cell activation. Differences in the effect of anti--chain and -chain Ab have been reported on thymocytes. Anti--chain Ab but not anti--chain reagents cause long-term TCR down-modulation. However, both types of Ab result in TCR cross-linking and activate early steps in signal transduction. In this study, we show that TCR in-ternalization and calcium flux, hallmarks of T cell activation, are similar with aV and aV treat-ment. Therefore, we have compared the gene ex-pression profiles of preselection thymocytes stimu-lated with these reagents. We find that aV treat-ment does not cause any significant change in gene expression compared with control culture condi-tions. In contrast, aV stimulation results in nu-merous changes in gene expression. The alter-ations of expression of genes known to be ex-pressed in thymocytes are similar to changes caused by positive thymic selection, suggesting that the expression of some of the genes without known roles in thymocyte development and of novel genes whose expression is found to be altered may also be involved in this process. J. Leukoc. Biol. 77