Generation of DC-based vaccine for therapy of B-CLL patients. Comparison of two methods for enriching monocytic precursors

P. Kokhaei; L. Adamson; M. Palma; A. Österborg; P. Pisa; A. Choudhury; H. Mellstedt
Cytotherapy. 2006;8(4):318-26.

Background
The generation of Ag-loaded DC under good manufacturing practice (GMP) conditions is logistically challenging and further compounded when the starting precursors need to be purified from B-CLL patients who have overwhelming numbers of circulating B-CLL cells and decreased numbers of monocytes.

Methods
We have previously demonstrated that DC with endocytosed B-CLL apoptotic bodies are powerful stimulators of anti-leukemic T cells. In this study we compared counterflow elutriation and immunomagnetic separation for enriching monocyte precursors, and evaluated the feasibility of generating DC from B-CLL patients and the effects of cryopreservation.

Results
Monocyte yield from a single leukapheresis product of a B-CLL patient varied from 1×108 to 10×108 total cells, from which 40-200×106 mature DC could be produced. Adequate numbers of monocytes could not be enriched from one patient with 0.2% monocytes in the leukapheresis product, and the target of 50×106 DC was barely achieved in another patient with 0.9% monocytes in the pheresed cells. These results suggested that successful production of DC is dependent on a minimum frequency of 1% CD14+ monocytes in the leukapheresis product. Cryopreservation of tumor cell-loaded DC yielded a recovery rate of 86±4.4% upon thawing, with a total viability of 90±2.8%. Most importantly, cryopreserved Ag-loaded DC retained their morphology, phenotype and function.

Discussion
The results demonstrate that adequate numbers of functional DC required for clinical therapy can be generated from patients who have >1% of CD14+ monocytes in the leukapheresis product. Moreover, Ag-loaded DC can be cryopreserved and recovered without significant change in phenotype or function.
Keywords: apoptotic bodies; B-CLL; cryopreservation; DC; immunotherapy

URL: http://www.informaworld.com/smpp/content~content=a755198732~db=all~order=page

Pub Med: http://www.ncbi.nlm.nih.gov/pubmed/16923607

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