High dose chemotherapy with autologous bone marrow support (ABMT) can achieve prolonged relapse-free survival in relapsed lymphomas, leukemias, and certain solid tumors. The principal morbidity and mortality relate to the infectious complications that occur during the 3-4 week aplasia until the marrow autograft recovers. Progenitor cells can be mobilized into the peripheral blood compartment by hematopoietic growth factors, used alone or after chemotherapy. We describe four trials using cytokine-mobilized peripheral blood progenitor cells (PBPC). In the first trial, PBPC collected after GM-CSF administration were used to augment marrow. Reconstitution of trilineage marrow function occurred promptly, resulting in short hospital stays and fewer platelet transfusions. In a second study, GM-CSF/chemotherapy-mobilized PBPC were used as the sole hematopoietic support during high dose chemotherapy. Granulocyte and platelet reconstitution was rapid. Time to hematopoietic recovery, transfusion requirements, and duration of hospital stay were all significantly improved for the patients receiving PBPC compared with similar patients receiving marrow alone. While most patients experienced prompt hematopoietic recovery they showed sluggish platelet engraftment. The next two trials built on the observation that a few PBPC alone could support both granulocyte and platelet recovery and were designed to test the feasibility of sequential high-dose therapies. In one trial, PBPC given with and without marrow made it possible to deliver two sequential cycles of high-dose therapy. The second trial utilized PBPC plus cytokines to deliver four cycles of dose-intensive chemotherapy at doses that could not be given with cytokine support alone.(ABSTRACT TRUNCATED AT 250 WORDS)