IL21 and B-cell chronic lymphocytic leukemia: Chronic lymphocytic leukemia (CLL) is characterised by accumulation of monoclonal mature B-lymphocytes in the circulation and tissues.[1, 2] The malignant lymphocytes depend on micro-environmental cues and factors for accumulation and survival.[3, 4] A myriad of factors that support CLL cell growth and proliferation are described including secreted cytokines such as IL6, IL21, and IL4, cell-contact elements such as CD40-CD154, and integrin-ligand interactions.[3] These reports have mainly addressed the effects of the microenvironment on the phenotype of CLL cells.