Cellular calibrators to quantitate T-cell receptor excision circles (TRECs) in clinical samples

► T‐cell receptor excision circle (TREC) count by PCR shows thymic output of T cells. ► An EBV B‐cell line was made with a single copy of the TREC sequence. ► Graded TREC-EBV cell numbers added to T-depleted blood constituted calibrators. ► TREC copy number was proportional to the number of TREC-EBV cells. ► TREC-EBV cells are as a universal cellular calibrator for TREC assays.