Abstract
Rationale: evaluation of the T-cell receptor (TCR) Vβ-chain repertoire by PCR-based CDR3 length analysis allows fine resolution of the usage of the TCR Vβ repertoire and is a sensitive tool to monitor changes in the T-cell compartment. A multiplex PCR method employing 24 labeled upstream Vβ primers instead of the conventionally labeled downstream Cβ primer is described. Method: RNA was isolated from purified CD4 and CD8 T-cell subsets from umbilical cord blood and clinical samples using TRI reagent followed by reverse transcription using a Cβ primer and an Omniscript RT kit. The 24 Vβ primers were multiplexed based on compatibility and product sizes into seven reactions. cDNA was amplified using 24 Vβ primers (labeled with tetrachloro-6-cardoxyfluorescein, 6-carboxyfluorescein, and hexachloro-6-carboxyfluorescein), an unlabeled Cβ primer, and Taqgold polymerase. The fluorescent PCR products were resolved on an automated DNA sequencer and analyzed using the Genotyper 2.1 software. Results: Vβ spectratypes of excellent resolution were obtained with RNA amounts of 250 ng using the labeled Vβ primers. The resolution was superior to that obtained with the labeled Cβ primer assay. Also the numbers of PCRs were reduced to 7 from the 12 required in the Cβ labeling method, and the sample processing time was reduced by half. Conclusion: The method described for T-cell receptor Vβ-chain repertoire analysis eliminates tedious dilutions and results in superior resolution with small amounts of RNA. The fast throughput makes this method suitable for automation and offers the feasibility to perform TCR Vβ repertoire analyses in clinical trials.
