Collection of mobilized blood progenitor cells for hematopoietic rescue by large-volume leukapheresis

Mobilized blood progenitor cells rapidly reconstitute hematopoiesis in patients after dose-intensive chemotherapy. However, optimal timing and methods of mobilized blood progenitor cell collection have yet to be fully defined.

The utility of large-volume leukapheresis (LVL; > 15 L blood processed) in collecting target doses of mononuclear cells (7 x 10(8)/kg) for use in autologous hematopoietic rescue was investigated. LVL was begun at a standardized interval (14 days) after a course of limited chemotherapy and subsequent daily recombinant human granulocyte-macrophage-colony-stimulating factor administration to mobilize blood progenitor cells into the circulation. With each LVL procedure, mononuclear cells, colony-forming units-granulocyte-macrophage (CFU-GM), burst-forming units-erythroid, mixed colonies, total clonogenic progenitor cells, and CD34+ cells collected per kg of patient weight were counted. After high-dose chemotherapy and infusion of cryopreserved mobilized blood progenitor cells, the days needed for neutrophils to reach levels of > 0.5 x 10(9) per L and for platelets to reach levels of > 20 x 10(9) per L were recorded.

In 14 previously treated cancer patients, an average of 28.9 +/- 4.9 L of blood was processed per LVL (n = 35) to collect medians of 2.5 x 10(8) mononuclear cells per kg (range, 1.0-7.4), 14 x 10(4) CFU-GM per kg (0-208), 27 x 10(4) clonogenic progenitor cells per kg (0-370), and 2.8 x 10(6) CD34+ cells per kg (0-112.5). Fifty-seven percent of patients (8/14) required one or two LVL procedures to collect adequate blood progenitor cells (range, 1-4). After dose-intensive chemotherapy, 13 patients received medians of 6.8 x 10(8) mononuclear cells per kg (range, 5.1-9.9), 53 x 10(4) CFU-GM per kg (9-208), and 12 x 10(6) CD34+ cells per kg (3.6-112.5). Rapid hematopoietic reconstitution occurred with 10 days (range, 8-12) and 9 days (6-15), respectively, for neutrophil and platelet recoveries.

Scheduled LVL, beginning on Day 14 after the administration of granulocyte-macrophage-colony-stimulating factor following chemotherapy, is a convenient and efficient method of collecting blood progenitor cells. The mononuclear cells so obtained effected consistent and rapid hematopoietic reconstitution in a highly reproducible manner in a group of heavily treated patients.