B-cell target DNA quantity is a critical factor in the interpretation of B-cell clonality by PCR.
Criteria for the assessment of clonality by Southern blotting are well established but this is not the case for polymerase chain reaction (PCR)-based assays. Our studies, and infrequent reports in the literature, indicate that B-cell clonality may be erroneously inferred if only small numbers of polyclonal B-cells are present in test samples. In order to establish criteria to minimise the false positive assignment of B-cell clonality, DNA was analysed in a semi-nested PCR to detect rearrangement of the immunoglobulin heavy chain gene using a range (1 microgram-0.1 ng) of target DNA amounts from four tonsils and five lymph nodes showing reactive follicular hyperplasia, and from six B-cell lymphomas. A discrete, narrow band of PCR product of constant size was detected throughout the range of target DNA amounts in most lymphomas indicating the presence of a monoclonal B-cell population. In contrast, from the non-malignant tonsils and lymph nodes, larger target amounts generated a broad band of PCR products indicating populations of polyclonal B-cells, but smaller target amounts generated discrete, narrow PCR product bands of inconstant size indicating oligo- or monoclonal B-cell populations. Results of this study demonstrate that a range of DNA target amounts should be tested when the proportion of B-cells in a sample is unknown, thus preventing the analysis of insufficient target DNA which may lead to the false assignment of clonality.
Taylor
J M
JM
Western Australian Centre for Pathology and Medical Research, Queen Elizabeth II Medical Centre, Nedlands, Australia.
Spagnolo
D V
DV
Kay
P H
PH
D002999:Clone Cells; D004247:DNA / Q000032:analysis*; D015322:Gene Rearrangement, B-Lymphocyte; D005803:Genes, Immunoglobulin; D006801:Humans; D008198:Lymph Nodes / Q000503:physiopathology; D016393:Lymphoma, B-Cell / Q000235:genetics; D014066:Palatine Tonsil / Q000503:physiopathology; D016133:Polymerase Chain Reaction
D004247:DNA