Induction of myeloma-specific cytotoxic T lymphocytes ex vivo by CD40-activated B cells loaded with myeloma tumor antigens.

We investigated to establish CD40-activated B cells (CD40-B cells) as alternative antigen-presenting cells (APCs) for the induction of myeloma-specific cytotoxic T lymphocytes (CTLs). To generate CD40-B cells, peripheral blood mononuclear cells were co-cultured with CD40L-transfected J558 cells in the presence of IL-4, insulin, transferrin, and cyclosporine for 14 days, and pulsed with myeloma lysates. The CD40-B cells consistently expressed high levels of CD80, CD86, CD54, CCR7, and HLA-DR. The CD40-B cells produced IL-12, IFN-gamma, and IL-6 during the culture period, but not IL-10. In addition, the CD40-B cells showed potent allogeneic T-cell stimulatory capacities that depended on the dose ratio and had the potential to polarize naïve T cells into Th1 subsets. The CD40-B cells loaded with tumor lysates induced strong target-specific CTLs, based on large numbers of IFN-gamma secreting cells and higher cytotoxic activity against target cells compared to the CD40-B cells without the tumor lysates. These results suggest that CD40-B cells loaded with myeloma lysates might provide alternative APCs for cellular immunotherapy in patients with myeloma.

The dysfunction and abnormal signaling pathway of dendritic cells loaded by tumor antigen can be overcome by neutralizing VEGF in multiple myeloma.

We investigated whether dendritic cells (DCs) from multiple myeloma (MM) patients were affected by loading tumor antigens and whether the defective DC function associated with MM could be overcome by the neutralization of VEGF. MM-specific DCs were generated by loading tumor lysates from myeloma cells at diagnosis or relapsed/progressive state, respectively. DCs loaded with tumor lysates showed lower phenotypic maturation, less T cell stimulatory capacity, less cytotoxic T lymphocyte activities, and highly abnormal cytokine secretions of IL-6 and IL-12, compared to myeloma lysate-unloaded DCs. The levels of VEGF, phospho-STAT3 and phospho-ERK1/2 in DCs were significantly higher with loading myeloma lysates. After the neutralization of VEGF activity, the DC function, signal transduction and cytokine production returned to normal. The defective function of DC in patients with MM is significantly affected by loading tumor antigens, correlating with abnormal STAT3 and the NF-kappaB signaling pathway, and neutralization of VEGF can overcome this DC dysfunction through the elimination of abnormal signal transduction.