The finding of a clonal B or T cell population can be used to support a diagnosis of a malignant B- or T-cell proliferation, but MUST always be interpreted with other histological and clinical data. This is based on the principle that all cells of a malignancy have a common clonal origin and show clonally (identically) rearranged immunoglobulin (Ig) or T-cell receptor (TCR) genes, whereas reactive lymphoproliferations show polyclonal (heterogeneous) rearranged Ig or TCR genes. B and T cell clonality studies can also be used to compare lymphoid proliferations at multiple sites or past and present samples, to distinguish between recurrence and new disease. Clonal B-cell populations are detected by analysis of the immunoglobulin heavy (IgH) and light chain (IgK and IgL) genes (van Dongen 2003 Leukemia 17: 2257). Clonal T-cell populations are detected by analysis of the TCRg, TCRb and TCRd genes. Clonal TCRg  gene rearrangements are detected using 4 multiplex fluorescent PCRs (Wickham 2000 J.Clin Pathol:Mol Pathol 53(3):150). Clonal TCRb  and TCRd gene rearrangements are detected using BIOMED Kits (InVivoScribe, California , USA). All products are analysed using an ABI 3130TM DNA sequencer.

Laboratory contact: Dr Caroline Wickham 01392 408252 caroline.wickham@nhs.net

Clinical contact: Dr Paul Kerr 01392 402917 paul.kerr1@nhs.net

The laboratory participates in the NEQAS LI IgH/TCR Clonality Programme.