IL2 and lymphoma: When compared to spleen cells stimulated for 4 hours with PMA and Ionomycin (Spleen+P/I), all lymphoma cell lines used here (RMA, RMA-S, YAC-1 and A20 cells) produced high quantity of IL-2 without prior stimulation, with the A20 cells producing the highest quantity by intracellular staining and by measuring secretion of IL-2 (Fig. 6A and supplementary Fig. 6B).