Differential mobilization of CD34(+) cells and lymphoma cells in non-Hodgkin's lymphoma patients mobilized with different growth factors

Co-mobilization of CD34(+) cells and tumor has been documented in patients with different types of cancer undergoing peripheral blood stem cell transp lantation (PBSCT). Conflicting reports were published regarding the role of various growth factors in tumor cells mobilization, hence we studied the e xtent of CD34(+) cells and lymphoma cell mobilization in 35 non-Hodgkin's ( NHL) patients primed by cyclophosphamide (Cy) in combination with granulocy te colony-stimulating factor (GCSF) (A, 13 patients), granulocyte-macrophag e (GM)-CSF (B, 10 patients), or GM-CSF followed by G-CSF (C, 12 patients). CD34(+) cells were quantitated by flow cytometry and lymphoma cells by the TaqMan Real Time PCR for bcl-2 gene rearrangement. Successful collection in 4 days of greater than or equal to2 x 10(6) CD34(+) cells/kg needed for pr ompt engraftment was obtained in 76%, 60%, and 58% of patients in arms A, B , and C, respectively. Lymphoma cell mobilization was detected in 35% patie nts tested, 78% of which had follicular lymphoma. Lymphoma cell mobilizatio n was similar in the three arms of the study, however, presence of lymphoma cells was prevalent in patients who failed to mobilize the amount of 0.4 x 10(6) CD34(+) cells/kg in 2 days ("poor mobilizers") and reached 42%, comp ared to 17% in the "successful mobilizers" group of patients. Lymphoma cell contamination in PBSCs was detected proportionately in the peripheral bloo d and in the bone marrow. We conclude that bcl-2 gene rearrangement is prev alent in patients with follicular histology, and, in these patients, an inv erse relationship was observed between mobilization of CD34(+) cells and ly mphoma cells. Our results explain the high relative risk (1.98) for mobiliz ation in patients with follicular histology.