In order to demonstrate the feasibility of mobilization, enrichment and engraftment of autologous peripheral blood CD34+ cells in patients with relapsed lymphoma, 59 peripheral blood progenitor cell (PBPC) collections from 21 patients were enriched for CD34+ cells using CEPRATE SC (CellPro, Bothell, WA, USA) immunoaffinity column. Following high-dose chemotherapy, a mean of 17 x 10(8) (range, 3-34) nucleated cells/kg containing 8.7 x 10(6) (0.3-26) CD34+ cells/kg were re-infused. Blood cell recovery in these patients was compared to engraftment capacity of unenriched PBPCs in a cohort of lymphoma patients treated with an identical high-dose chemotherapy regimen. Neutrophil and platelet engraftment was rapid in both groups including five patients who received < or = 1 x 10(6) CD34+ cells/kg. After infusion of CD34+ enriched cells, neutrophils exceeded 0.5 x 10(9)/l in 11 (8-14) days and platelets exceeded 20 x 10(9)/l (untransfused) in 15 (9-39) days. In order to optimize the immunoaffinity column utilization we stored the first PBPC collections overnight at 4 degrees C and combined them with the next day's collection prior to the CD34+ enrichment procedure in 11 patients. This maneuver resulted in a significant decrease in the CD34+ cell recovery (resulting in reinfusion of a mean of 42% less CD34+ cells). Although overnight storage did not affect neutrophil engraftment, platelet engraftment was prolonged in this group of patients even when > 2.0 x 10(6) CD34+ cells/kg were re-infused. The overnight storage procedure should be further evaluated for its effects on the CD34+ immunoaffinity enrichment procedure, megakaryocyte progenitors and platelet engraftment. We conclude that CD34+ cells enriched from peripheral blood result in rapid engraftment after high-dose chemotherapy in patients with advanced lymphoma that is comparable to that of patients receiving unenriched PBPCs.