IL-4 effects on proliferation of GCB-like and ABC-like DLBCL lines. (A) Effect of IL-4 on proliferation of ABC-like (OCILY10 and OCILY3) and GCB-like (SUDHL6, SUDHL4, and OCILY19) DLBCL cell lines. DLBCL cells were plated (10 × 10³ cells/well, in triplicates) in 96-well flat-bottom plates with and without IL-4 (100 U/mL) for 56 hours. The cell proliferation was measured by determining incorporation of 1 μCi (0.037 MBq) [³H]-thymidine (³H]TdR) added to the last 8 hours of culture. CPM indicates counts per minute. Error bars depict SD. (B) Effect of IL-4 on cell cycle in the ABC-like OCILY10 cell line. OCILY10 cells were grown in complete media alone or in the presence of IL-4 (100 U/mL). Cells were stained with propidium iodide as described in “Cell proliferation and cell-cycle analyses” and analyzed by flow cytometry. The percentage of cells in G1 phase (numbers in graphs) is increased following IL-4 treatment. A similar effect was also observed in the OCILY3 cells but not in the SUDHL4, SUDHL6, or OCILY19 cells (data not shown).