Fig. 3

Human myeloma cell clonogenicity. Colonies were counted by microscope after 2–3 weeks of culturing. IFN-γ and BCGV-treated RPMI8266 cells were plated with or without MM-Th2 cells in a clonogenic assay (tumor cells: 10,000/well). Results are the mean ± SEM. (error bars) of three separate experiments; * p < 0.05. (A) MM-Th2 cells significantly increased the clonogenicity of treated-RPMI8266 cells in a Th2: tumor cell ratio-dependent manner; * p < 0.05. (B,C,D,F) MM-Th2 cells groups versus non-MM-Th2 cells groups (Th2/tumor ratio of 20:1). Clonogenicity was significantly enhanced by MM-Th2; * p < 0.05, but reduced by anti-HLA-DR and Transwell; ^# p < 0.05. (C) Clonogenicity of treated-RPMI8266 cells were not affected by MM-CTL cells and non-MM-Th2 cells compared with by MM-Th2; ^# p < 0.05. (D) Requirements for cell–cell contact. MM-Th2 cells were either plated along with treated-tumor cells or separated from treated-tumor cells by a transwell insert membrane. (E,F) Untreated-tumor cells and tumor cells treated only with IFN-γ (Non-BCGV-treated-PRMI8266) were not affected by MM-Th2 cells compared with treated-RPMI 8266; ^# p < 0.05. (G,H) Clonogenicity of primary myeloma cells (n = 4). Tumor cells treated with IFN-γ and BCGV (treated-primary myeloma cells) were cultured in the presence or absence of allogeneic Th2 cells (MM-Th2) at a ratio of 1:20 (tumor: Th2 cells, tumor cells: 100,000/well) in the clonogenic assay. MM-Th2 cells significantly increased the clonogenicity of treated-primary myeloma cells; * p < 0.05, but this effect was reduced by anti-HLA-DR; ^# p < 0.05. Untreated-primary myeloma cells were not affected by MM-Th2 cells. (b, g) Control IgG2b did not repress the enhancement of clonogenicity produced by MM-Th2 cells