Qiasymphony kits

DNA was isolated from cryopreserved SF or PB samples using QIAsymphony kits (Qiagen, Redwood City, CA). HLA-B low-resolution typing was performed by Sequence-Specific Oligonucleotide method using LABType typing kit (One Lambda, Canoga Park, CA). The HLA-B27 positivity was determined by the presence of the HLA-B27 allele.

DNA was extracted using the DNeasy or QIAsymphony kits (both from Qiagen) according to the manufacturer's instructions. The TCR genes were sequenced using the ImmunoSEQ sequencing service (Adaptive Biotech), as previously described.²⁹ Briefly, ImmunoSEQ uses a standardized quantity of quality‐controlled DNA for the sequencing assay that consists of a multiplex PCR assay spanning recombined TCRα and TCRβ genes at a length that covers the entire CDR3 region and is capable of identifying both the V‐ and J‐genes for TCRα. Illumina platform was used to perform the amplicon sequencing (https://www.illumina.com/systems/sequencing‐platforms.html). The IMGT (www.imgt.org) database provided the definitions for TCRα sequences. A synthetic repertoire of TCRs and barcoded, spiked‐in synthetic templates was utilized to correct primer bias. Only in‐frame sequences were included in the analysis.