Background: Mononuclear cells (MNCs) of severely impaired acute myeloid leukemia (AML) patients may be collected by leukapheresis for large-scale generation of dendritic cells (AML-DCs) under good manufacturing practice (GMP) conditions for adoptive immunotherapy.
Study design and methods: In five end-stage AML patients, a leukapheresis procedure was performed with a cell separator (either COBE Spectra [Gambro BCT] or Amicus [Baxter]). For large-scale AML-DC generation, the MNCs of a single leukapheresis concentrate were isolated by density gradient and plated into a cell factory under GMP conditions. The AML-DCs were harvested on Day 8 of culture, and their viability, the mature morphology, and the phenotype were evaluated. The AML-DCs were injected subcutaneously into five AML patients up to four times at a biweekly interval.
Results: All AML patients entered the leukapheresis procedure with a highly pathologic blood count. In a mean separation time of 198 +/- 33 minutes, a mean of 1.3 +/- 0.2-fold the total blood volume was processed with a white blood cell (WBC) yield of 9 x 10(9) to 70 x 10(9) per collection dependent on the precollection WBC count. After density gradient a mean of 2.2 x 10(9) +/- 0.3 x 10(9) MNCs were plated into a cell factory. This resulted in a mean viable and mature DC yield of 0.01 x 10(9) of MNCs.
Conclusion: The leukapheresis procedure is a feasible and safe procedure even in patients with hematologic malignancies and highly pathologic blood counts. Sufficient amounts of MNCs can be collected in leukopenic patients and the large-scale generation of AML-DCs in cell factories under GMP conditions yields in an adequate quantity of viable and mature AML-DCs.