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-Ձ 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.

Keywords: Dendritic cells, Myeloma, Lysate, Cell line