Large-volume leukapheresis (LVL, 15-35 L) was performed in two groups of patients (n = 10) with hematologic malignancies to obtain peripheral blood stem cells for bone marrow rescue following high-dose chemotherapy. The target cell count was 7 x 10(8) mononuclear cells (MNCs = lymphocytes and monocytes) per kg of body weight. Group A patients (n = 4) were studied on Day 1 of LVL, and components were collected from them as four sequential samples. Total MNCs collected averaged 1.29 x 10(10), total colony-forming-units granulocyte-macrophage (CFU-GM) averaged 12.1 x 10(6), and a 1.8-fold mobilization of CFU-GM was observed (p < 0.05, Sample 1 vs. Sample 4). Group B patients (n = 6) were studied throughout the three consecutive planned days of 5-hour LVL. An average of three LVL procedures per patient was performed (range, 1.25-4), and an average of 27 L (range, 24-33) of blood per LVL was processed. The blood:ACD-A ratio was 24:1 with 3000 units of heparin per 500 mL of ACD-A; heparin was also added to the collection bags. The component had an average hematocrit (Hct) of 0.02 and MNC content of 93 percent. The patients' pre-LVL and post-LVL average Hct varied significantly (before Day 1, 0.36 +/- 0.08; after Day 3, 0.28 +/- 0.06; p < 0.05). Platelet counts also decreased, with post-Day 3 counts averaging 19 percent of the average pre-Day 1 counts (p < 0.05). A decrease in the average MNC count after LVL was significant on Day 1 only (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)