OBJECTIVETo detect the contaminating minimal residual disease (MRD) in autologous peripheral blood stem cells (APBSC) and evaluate its impact on the prognosis of non-Hodgkin's lymphoma NHL patients.

METHODSMinimal residual disease was detected in 72 APBSC samples from 33 NHL patients through PCR or PCR combined with DNA single-strand conformation polymorphism analysis (SSCP) with the BCL-2/IgH, clonal rearrangement of IgH and TCR gamma gene as markers. Minimal residual disease was also monitored in bone marrow samples collected pre-, post-induction chemotherapy and post-transplantation.

RESULTSMRD was positive in 17/72 (23.6%) APBSC samples. The incidence of positive MRD in bone marrow pre-, post-induction chemotherapy and post-transplantation was 44.0% (11/25), 28.1% (9/32) and 11.5% (3/26) respectively. Six (66.6%) of 9 patients with positive MRD in pre-mobilization bone marrow, compared with 2 (8.7%) of 23 patients with negative MRD in bone marrow, were positive in contamination (P < 0.01). The estimated overall 3-year post-transplantation survival rate for patients with positive and negative MRD in their APBSC would be 71.4% and 71.2% respectively, and the estimated 3-year disease free survival rates of 25.0% and 61.5% respectively (P = 0.53).

CONCLUSIONAPBSC collected from NHL patients after mobilization by chemotherapy combined with colony stimulating factor may be contaminated by lymphoma cells. The presence of minimal residual disease in bone marrow at mobilization may increase the incidence of APBSC contamination.