Transformation efficiency by Herpesvirus saimiri is not a limiting factor in clonal CD8pos T cell outgrowth.

The routine transformation of human CD8(pos) T cells by Herpesvirus saimiri has so far not been achieved in the case of pre-expanded antigen-specific CTLs. Here we transformed 73% of polyclonal EBV-specific CD8(pos) T cell cultures using an optimized culture medium supplemented with IL-2, IL-7, IL-12, and TGF-beta(1). Still, antigen-specific cytotoxicity was frequently lost and analysis of the TCR Vbeta-chain repertoire revealed a variable outgrowth of several initially subdominant populations. Limiting dilution cloning of cells in the presence of high titers of HVS did not result in clonal transformation but in the rapid loss of the viral genome in outgrowing clones. In summary, our data suggest that transformation of CD8(pos) T cells out of bulk cultures can be routinely achieved, while viral transformation itself remains an infrequent event on a per cell basis. The practical use of the improved immortalization of antigen-expanded CD8(pos) T cell lines, however, is limited by the arbitrary outgrowth of subdominant populations of unpredictable specificity.

Efficient chemokine-dependent migration and primary and secondary IL-12 secretion by human dendritic cells stimulated through Toll-like receptors.

Recent findings have demonstrated the properties of cell migration and cytokine secretion to be mutually exclusive and linked them to different functional subpopulations of dendritic cells (DCs). We studied human monocyte-derived DCs after stimulation with peptidoglycan (PGN), poly(I:C), lipopolysaccharide (LPS), and R848 (resiquimod) and found the resulting mature DCs to express CCR7, to migrate toward CCL19 and to be efficient primary interleukin (IL)-12 producers. Importantly, the potential for secondary production of large amounts of IL-12p70 in response to CD40 ligation was also preserved after stimulation by all Toll-like receptor (TLR) ligands. Differences between the TLR ligands were seen in the primary secretion of IL-12 and IL-23, in the survival of the DCs and in the expression of CD38. Finally, DCs stimulated by R848 were efficient in expanding peptide-specific CD8-positive T cells capable of peptide-specific target cell lysis. Together, our data suggest that TLR ligands induce the generation of mature DCs that integrate migratory and cytokine secretory capacity as well as cytotoxic T lymphocyte (CTL) stimulatory properties.