This report summarizes our results of sequential treatment with IL-3 and GM-CSF following high-dose chemotherapy with respect to the yield and composition of peripheral blood stem cells (PBSC). Eight patients with high-grade non-Hodgkin's lymphoma were included in the study. Starting 24 h after high-dose cytosine arabinoside (Ara C)/mitoxantrone, IL-3 was given for 6 days, followed by GM-CSF. The increase of circulating hematopoietic progenitor cells during leukocyte recovery varied substantially from patient to patient. Up to a 22-fold interindividual difference was observed for the peak levels of CD34+ cells. A special focus of our study was the antigenic profile of the CD34+ PBSC. On analysis of the antigenic profile of the CD34+ cells, the proportion of CD34+/HLA-DR- and CD34+/CD38- cells representing non-committed hematopoietic stem cells was consistently < 5%. The vast majority of CD34+ cells was found to coexpress CD33 (86.3 +/- 2.1%, mean +/- SEM), reflecting myeloid lineage commitment. CD71 antigen was present on 47.4 +/- 3.0% CD34+ cells with two populations (CD71dim/bright), while the percentage of early B lymphoid (CD34+/CD19+) progenitor cells was extremely low (0.38 +/- 0.13%). We therefore conclude that the cytokines currently available such as G-CSF, GM-CSF or IL-3 facilitate an ontogenetic phenomenon supporting the redistribution of hematopoietic progenitor cells after cytotoxic treatment. Six patients were autografted with the IL-3/GM-CSF-exposed blood stem cells following high-dose conditioning therapy. It is worth noting that no additional BM or hematopoietic growth factors were given post-transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)