Fig. 3.

CD40-B cells efficiently process FluM1 antigen but not Mart1 M26 or Cyp239 antigen. Target cells (25,000 cells/well) were coincubated with the FluM1 (left column)-, Mart1 M26 (center column)-, or Cyp239 (right column)-specific T-cell clones (500 cells/well) in triplicate, and γ-interferon secretion was determined by ELISPOT. CD40-B cells pulsed with specific peptide (FluM1, M26, or Cyp239), but not control peptide, specifically stimulated all three T-cell clones. CD40B cells and dendritic cells (DC) nucleofected with 20 μg of RNA encoding the specific full-length antigen for FluM1 (left) but not control RNA stimulated the FluM1 clone (left, middle). In contrast, CD40B cells or dendritic cells (DC) nucleofected with Mart1 RNA (center) or Cyp1B1 RNA (right) poorly stimulated the T-cell clones. In comparison, RNA encoding all three antigens were nucleofected into K562/A2 cells and were efficiently presented to the T-cell clones (bottom row)