It was the objective of our study to evaluate the efficacy of a sequential high-dose therapy with peripheral blood progenitor cell (PBPC) support in patients with low-grade non-Hodgkin's lymphoma (NHL). Since July 1991, 48 patients (23 male/25 female) with a median age of 43 years (range 26-55) were included in the study. At the time of entry, 28 patients were in first and seven in second or higher remission. Twelve patients had relapse of disease and one patient had tumor progression. PBPC were collected during granulocyte colony-stimulating factor (G-CSF)-enhanced leukocyte recovery following treatment with high-dose cytarabine and mitoxantrone (HAM). A median of two leukaphereses (range 2-7) resulted in 6.9 x 10(6) CD34+ cells/kg (median, range 2.1 x 10(6)-38.8 x 10(6)). A comparison was made between the harvests obtained from patients in first remission and those from patients in second remission, in relapse or progressive disease. Patients mobilized in first remission tended to have a greater collection efficiency for CD34+ cells comprising a significantly greater proportion of more primitive CD34+/Thy-1+ progenitor cells. Conversely, leukapheresis (LP) products collected during first remission contained a significantly smaller proportion of CD34+/CD45RA+ cells and CD34+/c-kit+ cells, subsets which reflect a more differentiated progenitor cell stage. Following high-dose therapy and PBPC autografting, the median time to reach platelets > or = 20 x 10(9)/l and neutrophils > or = 0.5 x 10(9)/l and 12 and 13 days, respectively. Two patients died of treatment-related toxic organ failure. Thirty-nine patients are alive in remission after a median follow-up time of 15 months (range 1-31), while seven patients relapsed between 5 and 29 months post-transplantation. Except for one patient autografted in first remission, the patients with relapse had a history of previous relapse or progressive disease. Since the probability of disease-free survival appears to be related to the disease status at the time of autografting, PBPC-supported high-dose therapy including total body irradiation should be investigated further for patients with low-grade NHL while they are in first remission.