Improved PCR assay for the detection of antigen receptor gene rearrangements

The detection of small numbers of leukaemia cells in patients with occult disease has important clinical implications. Leukaemia is a monoclonal disease which frequently displays clonal rearrangement of the T-cell receptor gamma (TCR gamma) and/or immunoglobulin heavy chain (IgH) gene. Clone-specific junctional sequences arising as a result of these gene rearrangements provide potentially valuable targets for monitoring residual disease by the polymerase chain reaction (PCR). However, existing strategies for PCR amplification of these clone-specific rearrangements frequently lack the necessary sensitivity or specificity, due either to the small size of the target junctional region, or to interference resulting from polyclonal IgH or TCR gamma rearrangements in normal lymphocytes. We have previously described a novel PCR strategy to overcome these obstacles which is based on the design of two overlapping clone-specific PCR primers which span the junctional region. We now describe a modification to this strategy which employs relatively short clone-specific primers which further increases the level of specificity. This new method should improve the detection of residual cells, particularly in those cases displaying small junctional regions. Unlike other strategies, specificity is generated from the initial round of amplification. This non-radioactive technique should thus prove effective in monitoring residual leukaemia in patients.