The Impact of Exosomes/Microvesicles Derived from Myeloid Dendritic Cells Cultured in the Presence of Calcitriol and Tacalcitol on Acute B-Cell Precursor Cell Lines with MLL Fusion Gene

Vitamin D analogs (VDAs) may directly inhibit the growth of normal and malignant (derived from acute lymphoblastic leukemia (ALL)) B cells, as both types of cells express vitamin D receptor (VDR). We performed anti-proliferative, morphology tests and phenotyping to evaluate the sensitivity of monocytes and iDCs (immature myeloid-derived dendritic cells) on calcitriol and tacalcitol treatment, phenotyping, morphology, and size distribution measurement to determine the characteristics of microvesicles (MVs) and exosomes (EXs) derived from them and, finally, phenotyping and Elisa test to determine the effects of VDAs on modulation of the phenotype of B cells through extracellular vesicles (EVs) released by iDCs. Our results confirmed that both SC cells and iDCs were sensitive to the VDAs and showed altered surface expression of markers associated with monocyte differentiation, which was resulting in the phenotypic changes in EVs derived from them. We also showed that obtained EVs could change the morphology and phenotype of ALL-B-derived precursor cells in a different way, depending on their origin. The differential effect of VDAs on ALL-B cells, which was associated with increased or decreased expression of CD27, CD24, CD38, and CD23 expression, was observed. Hence, further studies to explain the modulation in the composition of EVs by VDAs are required.