A PCR assay for detecting clonal rearrangement of the TCR-γ gene

Background: The T-cell receptor gamma chain (TCR-gamma) gene has 11 functional variable (V) exons that can be organized into four subfamilies and four functional joining (J) exons that can be divided into two subfamilies. Method and Results: Three multiplex PCR reactions amplifying the TCR-gamma gene were developed. Primer combinations for multiplex PCR were chosen so that the V-region subfamily and J-region subfamily involved in a clonal band could be identified. Control primers from the protease inhibitor (PP) gene were also included in each reaction to verify the presence of amplifiable DNA. Fifty-six archived samples that had been tested by Southern blot for clonal rearrangement of the TCR-beta gene were analyzed with the TCR-gamma PCR protocol. Twenty-one of 56 samples were TCR-beta positive by Southern blot and thus expected to be positive with TCR-gamma PCR. Thirty-five of 56 samples were TCR-beta negative by Southern blot. Of these, 14 samples showed clonal rearrangement of the immunoglobulin heavy chain gene. The TCR-gamma PCR protocol showed a diagnostic sensitivity for detecting T-lineage clonality of 90%, with a diagnostic specificity for detecting T-cell lineage of only 74%. Conclusion: The PCR protocol described here performed well in comparison with a TCR-beta Southern protocol.