Enhanced T-cell activation and T-cell-dependent IL-2 production by CD83+, CD25high, CD43high human monocyte-derived dendritic cells

Although standardized protocols are widely used for the generation of monocyte-derived immunostimulatory dendritic cells (DCims), the inducibility of Th1 cells by DCims may considerably differ. As a measure for the quality of DCims generated from an individual donor at a certain time point, CD83 is used in combination with HLA-DR and CD86 to assess DC maturation. When phenotypically analyzing DCims, we identified a subpopulation (∼60%) of CD83+, CD86+, and HLA-DR+ DCims that co-expressed CD25. DC within a given DCims preparation identified by lower expression of CD83 and by selective expression of CD14, however, did not co-express CD25. In order to establish CD25 as an additional maturation marker of DCims, we studied the DC phenotype of these cells as well as the DC-dependent T-cell proliferation and T-cell cytokine production profile after co-incubation with sorted CD25high and CD25low subpopulations of CD83+, HLA-DR+, CD86+ DCims. CD25high DCims showed significant up-regulation of the DC activation molecule CD43 and induced increased levels of IL-2 secretion in allogeneic T-cells (170.7 ± 86.7 pg/mL) as compared to T-cells coincubated with CD25low DCims (86.6 ± 37.6 pg/mL) [p = 0.0224]. This was reflected by a significantly lower T-cell stimulatory capacity of CD25low DCims (84.0% of CD25high DCims, 1:10 ratio; p = 0.014) whereas the T-cell stimulatory capacity of CD25low DCims was much higher when compared to IL-10 induced regulatory DC (55.3% of CD25high DCims; 1:10 ratio). With regard to cancer vaccination protocols, we propose to use CD25 and CD43 as additional markers for DC quality control, assessment of maturational status, and positive selection.