Induction of Myeloma Cell Line-specific Cytotoxic T Lymphocytes using Monocyte-derived Dendritic Cells Pulsed with Myeloma Cell Line Lysates

BACKGROUND: In multiple myeloma (MM), the idiotype (ID) determinant of the paraprotein has been used for immunotherapy using dendritic cells (DCs). However, ID-specific immune responses showed limited clinical responses after the Id vaccination. Therefore, an alternative approach using DCs pulsed with other tumor antigens is required. METHODS: We investigated the possibility of immunotherapy for MM using myeloma cell line-specific cytotoxic T lymphocytes (CTLs), that were stimulated in vitro by monocyte-derived DCs pulsed with the myeloma cell line ysates. CD14+ cells isolated from the peripheral blood of HLA-A0201+ healthy donors were cultured in the presence of GM-CSF and IL-4. On day 6, the immature DCs were pulsed with the myeloma cell line lysates (IM-9: HLA0201+ and ARH-77: HLA0201+), and then maturation of DCs was induced by the addition of TNF- alpha for 2 days. CTL lines were generated by a 2 time stimulation with DCs to the autologous CD3+ T cells. RESULTS: DCs pulsed with myeloma cell lysates showed the production of IL-12p70, but less than that of unpulsed DCs. CTLs lines stimulated with the DCs pulsing, for the myeloma cell line lysates, showed potent cytotoxic activities against autologous target cells, but not against HLA-A2-cell lines (RPMI-8226). Mature DCs pulsed with the myeloma cell line lysates showed a higher stimulatory capacity for autologous CTL when compared with mature non-pulsed DCs. CONCLUSION: These results suggest that DCs pulsed with the myeloma cell line lysates can generate potent myeloma cell line-specific CTLs for the myeloma cell-based immunotherapeutic approach in MM.

A Bacterial Flagellin, Vibrio vulnificus FlaB, Induces Human Dendritic Cell Maturation

The motile marine bacterium, Vibrio vulnificus has a total of six flagellins. Flagellin is a structural component of flagellar filament in various locomotive bacteria and is the ligand of Toll-like receptor 5 (TLR5). TLRs, highly expressed on various types of cells including dendritic cells (DCs), recognize invading microorganisms and finally trigger host immune responses. In this study, we prepared all of six recombinant flagellin proteins and assessed the effect of six flagellins on IL-8 activation through TLR5 recognition. Although showed different activities, five out of the six flagellins stimulated significant IL-8 activation. We also investigated the immunomodulatory roles of Vv-FlaB, the crucial building block of V. vulnificus flagellar filament, on human dendritic cells. Treatment of immature DCs with Vv-FlaB resulted in an increased expression of co-stimulatory molecules and induced strong allo-T cell proliferative activities of the DCs. These results show that the Vv-FlaB may serve an epochal immune adjuvant possessing effective immunomodulatory activities.