Fig. 6.

Bortezomib enhances CTL killing of allogeneic tumor cells. BALB/c (H2^d) mice were primed with irradiated C1498 cells (H2^b) as described in Materials and Methods. Spleen cells were then harvested and restimulated with irradiated C1498 cells in vitro at a ratio of 20:1 for 5 days. CTL were collected and cultured with C1498 (H2^b) in the presence or absence of 4 nM bortezomib. Tumor cells were analyzed by flow cytometry and clonogeneic growth. (A and B) C1498 cells were gated on based on H2^b expression and forward- and side-scatter properties; the gated cells were analyzed for annexin V binding and propidium iodide incorporation at the end of 36-h incubation. (A) Representative dot plots. (B) Decreased numbers of live C1498 tumor cells (annexin V and propidium iodide negative). (C) Clonogeneic C1498 growth was determined after treatment with CTL in the presence or absence of bortezomib for 45 h. Representative data from one of two independent experiments are presented.