Comparison of CD34 and monocyte-derived dendritic cells from mobilized peripheral blood from cancer patients.

Dendritic cells (DCs) are potent antigen-presenting cells that are integral to the initiation of T-cell immunity. Two cell types can be used as a source for generating DCs: monocytes and CD34(+) stem cells. Despite many investigations characterizing DCs, none have performed a direct paired comparison of monocyte and stem cell-derived DCs. Therefore, it is unclear whether one cell source has particular advantages over the other, or whether inherent differences exist between the two populations. We undertook the following study to determine if there were any differences in DCs generated from monocytes or CD34(+) cells from mobilized peripheral blood. DCs were generated by culturing the adherent cells (monocytes) in interleukin-4 and GM-CSF for 7 days, or by culturing nonadherent cells (CD34(+)) in the presence of GM-CSF and tumor necrosis factor alpha for 14 days. The resulting DCs were compared morphologically, phenotypically, functionally, and by yield. We could generate morphologically and phenotypically similar DCs. Differences were encountered when expression levels of some cell surface markers were examined (CD86, HLA-DR). There was no difference in how the DCs performed in a mixed lymphocyte reaction (p = .3). Further, no statistical difference was discovered when we examined cellular (DC) yield (p = .1); however, there was a significant difference when yield was normalized to the starting number of monocytes or CD34(+) cells (p = .016). Together, these data demonstrate that differences do exist between monocyte-derived DCs and CD34-derived DCs from the same cellular product (apheresis) from the same individual.

Evidence for a mechanosensitive calcium influx into red cells.

Red cells exposed to glycophorin A reactive antibodies and lectins develop a non-specific cation permeability. To determine if this might be due to the activation of a non-selective mechanosensitive channel we have subjected red cells, loaded with a calcium responsive fluorescent probe, to filtration through 5 and 3 microm pores. Calcium entered 28% of normal red cells at the moment of deformation when 3 microm filtered, a finding consistent with the transient activation of a mechanosensitive channel. Red cells containing hemoglobin AC and AS had enhanced calcium responses to filtration. An increased influx of calcium in hemoglobin disorders might play a role in providing protection against Falciparum malaria.