IL6 and primary central nervous system lymphoma: Cytokines including interleukin-1 (IL-1), interleukin-6 (IL-6), and interleukin-10 (IL-10) have been demonstrated to inhibit the function of erythropoietin in vivo, and high IL-6 levels were thought to be the major factor for the development of anemia in DLBCL (27, 28); likewise, an elevated CSF level of IL-10 in PCNSL was associated with a shorter PFS (29).