Cytokine analysis of EOP 19-28z–transduced T cells stimulated on CD19⁺ AAPCs. EOP 19-28z–transduced T cells were plated on 3T3 fibroblast AAPCs expressing CD19. After 48 hours in culture, cell supernatants were assayed for cytokine levels. The cytokine levels were normalized to transduction efficiency. In addition, background cytokine levels measured on 3T3 fibroblasts that did not express CD19 were subtracted.