Background Myeloid leukaemic blasts can be converted into leukaemia derived dendritic cells (DCleu) with blastmodulatory Kit-I and Kit-M, which have the competence to regularly activate T and immunoreactive cells to gain anti-leukaemic activity or rather cytotoxicity. As innate and adaptive immune responses are notably promoted by the cytokine interferon gamma (IFNy), we hypothesised that the IFNy secretion could be a suitable parameter to display DC/DCleu mediated immunologic activity and even anti-leukaemic cytotoxicity.
Materials and Methods DC/DCleu were generated from leukaemic WB with Kit-I (GM-CSF + OK-432) and Kit-M (GM-CSF + PGE1) and used to stimulate T cell enriched immunoreactive cells. Initiated anti-leukaemic cytotoxicity was investigated with a cytotoxicity fluorolysis assay (CTX). Initiated IFNy secretion of innate and adaptive immune cells (T cells, TCD4+ cells, TCD8+ cells, NKCD56+ cells, NKCD161+ cells, CIKCD56+ cells, CIKCD161+ cells and iNKT) was investigated with a cytokine secretion assay (CSA). In some cases IFNy production was additionally evaluated with an intracellular cytokine assay (ICA). Conclusively, the IFNy secretion of immunoreactive cells was correlated with the anti-leukaemic cytotoxicity.
Results Significant amounts of DC and DCleu as well as migratory DC and DCleu could be generated with Kit-I and Kit-M without induction of blast proliferation. T cell enriched immunoreactive cells stimulated with DC/DCleu showed an increased anti-leukaemic cytotoxicity and an increased IFNy secretion of T, NK and CIK cells compared to control. Both the CSA and ICA yielded comparable amounts of IFNy positive innate and adaptive immune cells. The correlation between the IFNy secretion of immunoreactive cells and the anti-leukaemic cytotoxicity showed a positive relationship in T cells, TCD4+ cells, TCD8+ cells and NKCD56+ cells.
Conclusions We found blastmodulatory Kit-I and Kit-M competent to generate DC/DCleu from leukaemic WB. Stimulation of T cell enriched immunoreactive cells with DC/DCleu regularly resulted in an increased anti-leukaemic cytotoxicity and an increased IFNy dependent immunological activity of T, NK and CIK cells compared to control. Moreover the anti-leukaemic cytotoxicity positively correlated with the IFNy secretion in T cells, TCD4+ cells, TCD8+ cells, NKCD56+ cells. We therefore consider the IFNy secretion of innate and adaptive immune cells to be a suitable parameter to assess the efficacy of in vitro and potentially in vivo AML immunotherapy. The CSA in this regard proved to be a convenient and reproducible technique to detect and phenotypically characterise IFNy secreting cells of the innate and adaptive immune system.
Disclosure Information L.K. Klauer: None. O. Schutti: None. S. Ugur: None. F. Doraneh-Gard: None. N. Rogers: None. M. Weinmann: None. D. Krämer: None. A. Rank: None. C. Schmid: None. B. Eiz-Vesper: None. H.M. Schmetzer: None.
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