Detection of tumor cells in purged bone marrow and peripheral-blood mononuclear cells by polymerase chain reaction amplification of bcl-2 translocations.

Abstract

To compare bone marrow (BM) before and after purging with monoclonal antibodies (MAbs) and complement with peripheral-blood mononuclear cells (PBMNCs) for tumor-cell contamination by amplification of t(14;18) sequences using the polymerase chain reaction (PCR). Sixty patients with non-Hodgkin's lymphoma (NHL) undergoing autologous BM transplantation were evaluated. Six BM biopsies were performed at the time of harvesting and evaluated morphologically for tumor involvement. The harvested BM was treated with a panel of anti-B-cell MAbs directed against CD9, CD10, CD19, and CD20, followed by rabbit complement. Clonogenic assays were performed before and after purging. DNA was extracted and t(14;18) sequences amplified by PCR. PBMNCs collected by apheresis for back-up purposes were similarly evaluated. Fifteen patients (25%) were PCR-positive before BM purging. Following MAb- and complement-mediated purging, there was a reduction in the PCR-amplified signal in 10 patients (67%). There was no reduction in colony-forming unit granulocyte-macrophage (CFU-GM) colony growth following purging. Eight of these 15 patients (53%) had morphologic evidence of BM involvement at the time of harvesting. In these eight patients, only three had a reduction in the PCR-amplified products, as compared with all seven who were morphologically negative at the time of BM harvesting (P = .026). Fourteen of these 15 patients had PBMNCs collected near the time of BM harvesting and 12 (86%) were PCR-positive. BM purging with MAbs and complement results in reduction in the number of t(14;18)-positive tumor cells, especially in those patients who have no morphologic evidence of BM disease at the time of harvesting. Purged BM was less contaminated with t(14;18)-positive cells than unpurged PBMNCs, which were frequently contaminated with tumor cells.