Representative comparison of cases analyzed with the tri-color, one-color, and the IVS TCRG Gene Clonality Assay (Tubes A and B). A: PBL, 1 μg DNA. Note pseudoclonal spikes in tubes A and B of the TCRG Gene Clonality Assay. B: Diffuse large B-cell lymphoma, Southern blot result was negative for a TRB@ gene rearrangement. Both the one-tube assays and the BIOMED-2 assay show an oligoclonal result with multiple pseudoclonal spikes present. C: Reactive lymphocytosis, Southern blot result negative for a TRB@ gene rearrangement. Whereas the one-tube assays are negative, two peaks greater than 2× RPB are identified in IVS tube A (arrows) that would be interpreted as clonal using the 2× RPB threshold, but would be interpreted as negative if a 5× RPB threshold was used. D: Peripheral T-cell lymphoma, Southern blot result positive for a TRB@ gene rearrangement. Discordant results with a biallelic Jγ1/Jγ2 and a JγP rearrangement identified in the one-tube, tri-color method, the latter not identified in the IVS System. The peak in tube B is one-fifth the intensity of the clonal peak in A and is not JγP.