B2M and neoplasm: These results agree with the results of Kusano et al., who detected serum levels of sIL-2R in pretreated FL cases and found that stage III/IV, nodal lesions, bone marrow involvement, bulky tumor, elevated LDH, increased β2 M, high Follicular Lymphoma International Prognostic Index (FLIPI) and high FLIPI2 were significantly associated with high sIL-2R levels [27].