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Purpose.. Immunotherapy holds promise as a new strategy for the eradication of residual cells in acute myeloid leukaemia (AML). Leukaemic antigen presenting cells (APCs) combining optimal antigen presentation and tumour antigenicity could be used as potent T cell activators. For clinical purposes it is desirable to culture APCs under serum-free conditions. Therefore, we compared morphological, immunophenotypical and functional outcome of the serum-free culture of AML-APCs to their serum-enriched culture. Methods.. AML blasts (n=19) were cultured in the presence of either a cytokine mix or calcium ionophore (CI) for 14 and 2 days, respectively, in FCS-containing medium (FCS), StemSpan serum-free medium (SP) and CellGro serum-free medium (CG). After culture relative yields were calculated and immunophenotypic analysis of APC markers was performed. The mixed leukocyte reaction (MLR) was used to determine T cell stimulating capacity. Results.. Serum-free culture of AML-APCs resulted in comparable morphology, relative yields and immunophenotype to serum-enriched culture. By comparing both serum-free media we observed a trend towards a more mature phenotype of CI-cultured AML-APCs in SP. MLR showed that serum-free cultured cells have equal T cell stimulatory capacity in comparison with serum-enriched culture. Conclusion.. These data show that the serum-free culture of AML-APCs is feasible and that these APCs are comparable to serum-enriched cultured AML-APCs with regard to morphological, immunophenotypical and functional characteristics. These AML-APCs are suitable for the development of active specific immunisation protocols which meet the criteria for good clinical practise (GCP). [ABSTRACT FROM AUTHOR]

The ability of acute myeloid leukaemia (AML) cells to acquire dendritic cell (DC)-like characteristics in vitro with a rapid culture method based either on the phorbol ester PMA or calcium ionophores has been studied in comparison to conventional AML-DC cultures with the cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), tumour necrosis factor-alpha (TNF-α), interleukin-3 (IL-3), SCF, FLT3-L and IL-4. In all AML patients, antigen-presenting cells (APC) could be generated from leukaemic cells in 2 days by incubation with PMA or calcium ionophore (A23187 or ionomycin) in the presence as well as in the absence of IL-4. In 30 out of 36 patients APC could be generated after 2 weeks of culture in cytokine-enriched medium. AML-APC cultured with PMA or calcium ionophores immunophenotypically and functionally were at a more mature stage than those cultured in cytokine-enriched medium. The most mature APC were generated by calcium ionophore A23187 plus IL-4, as evidenced by the higher expression of CD40, CD80, CD86 and HLA-DR. Autologous T cell mediated cytotoxicity towards AML blast cells in vitro was observed in 2 cases tested. The persistence of cytogenetic abnormalities confirmed the leukaemic origin of the AML-APC. The generation of AML-APC was possible from freshly isolated as well as cryopreserved material. Our data show that generation of sufficient AML-APC by A23187 plus IL-4 is feasible, for vaccination purposes, in approximately 70% of AML specimens, offering a time-saving and cost-effective approach in preparing anti-leukaemia vaccines. [ABSTRACT FROM AUTHOR]