Immunomagnetic bone marrow (BM) and peripheral blood progenitor cell (PBPC) purging in follicular lymphoma (FL)

Abstract

Twenty-nine B cell follicular lymphoma (FL) patients had their BM (n = 12) or PBPC (n = 17) purged using a panel of monoclonal antibodies and immunomagnetic beads (IMB). The median recovery of nucleated cells (NC) and CD34⁺ cells was 59.3% (40.5–74) and 56.1% (30.8–82.9) in BM and 77.2% (64.7–88.3) and 73.5% (61.5–98.6) in PBPC (P < 0.0005). a median of >1.62 and >1.02 log of target cell depletion was achieved as judged by flow cytometry analysis in BM and PBPC, respectively. Of 29% of initial harvests that had a bcl2 PCR-amplified signal, 37.5% became PCR negative in the final purged products. Absorbed cells containing IMB–target cell complexes gave bcl2 rearrangement signal in 20% of samples in which the start and final purged components were negative. Twenty-three of 26 patients receiving an autologous purged product are evaluable for engraftment. Median time to reach an ANC > 0.5 × 10⁹/l and platelet count >20 × 10⁹/l was 21 (11–43) and 41 days (13–70) for BM (n = 9) and 14 (10–31) and 14 (8–37) for PBPC (n = 14) autografted patients (P = 0.01 and 0.001). One patient did not engraft and was rescued with a back-up BM. These data demonstrate that this indirect immunomagnetic technique is able to achieve a high grade of lymphoma cell depletion in BM and PBPC and that these purged products are capable of rapid engraftment after autologous transplantation.