library_construction_protocol: CD69-MHCI+ (M2) CD4SP thymocytes were FACS-sorted, pelleted and resuspended in RNA protect (Qiagen). All samples were stored at -80°C until RNA extraction. RNA isolation was performed by Qiagen, according to the RNeasy Mini/Micro kit (Qiagen). QIAseq® Immune Repertoire RNA Library kit (Qiagen), modified to include only TCRα-specific primers for both the reverse transcription and the target enrichment steps.