Maturation of dendritic cells by recombinant human CD40L-trimer leads to ahomogeneous cell population with enhanced surface marker expression and increased cytokine production

Dendritic cells (DC) have been shown to be potent inducers of specific cyto toxic T-cell responses both in vivo and in vitro. Furthermore, exposure to cytokines such as tumour necrosis factor (TNF)-alpha or CD40 triggering cha nges DC phenotype and cytokine production and may enhance the T-cell activa ting capacity of the DC. We studied DC phenotype and cytokine production as well as the T-cell proliferation and cytotoxic T lympocyte (CTL) activatio n induced by DC generated in vitro. In addition, the effect of exposure to recombinant human CD40L-trimer (huCD40LT) on these parameters was investiga ted. Effective differentiation of monocytes derived from freshly isolated p eripheral blood mononuclear cells (PBMC) was obtained with granulocyte macr ophage-colony stimulating factor (GM-CSF) and interleukin (IL)-4. The DC ex pression of human leucocyte antigen (HLA) molecules, CD80, CD83, and CD86 w as markedly enhanced by exposure to huCD40LT even compared to TNF-alpha exp osure. Only a moderate cytokine production was observed initially, while TN F-alpha addition or CD40 triggering, especially, induced enhanced productio n of IL-6 and IL-12 p40. Surprisingly, comparable induction of T-cell proli feration by a DC allostimulus or through the presentation of PPD, and influ enza M1-peptide specific CTL activity was obtained with nonmaturated (CD83( -)) and maturated (CD83(+)) DC. In conclusion, a final maturation of monocy te-derived DC through huCD40LT resulted in a highly homogeneous cell popula tion with enhanced surface marker expression and high production of pro-inf lammatory cytokines. In addition, the induction of responses to allo or rec all antigens presented by huCD40LT maturated DC was comparable to the respo nses obtained with the DC maturated through TNF-alpha exposure.