IL6 and Splenomegaly: In the chlorambucil-obinutuzumab arm, factors associated with an increase in cytokine and chemokine levels included Rai stage III/IV (IL-8, IL-18), bulky disease (≥ 5 cm: IL-10, TNFα), splenomegaly (IFNγ, IL-18, IL-6, IL-8, MIP-1α, TNFα), lower hemoglobin levels (IL-10, IL-8), lower platelet count (IL-18, MCP-1, MIP-1β), and higher absolute lymphocyte count (IFNγ, IL-10, IL-6, IL-8, MCP-1, MIP-1α, TNFα) (Online Resource Table S3).