Comparison of interleukin-1 beta expression by in situ hybridization in monoclonal gammopathy of undetermined significance and multiple myeloma

We investigated whether interleukin-1 beta(IL-1 beta) is differentially exp ressed in plasma cells from monoclonal gammopathy of undetermined significa nce (MGUS) and multiple myeloma (MM) patients because IL-1 beta appears to play a major role in the development of lyric bone lesions, the major clini cal feature distinguishing MGUS from myeloma, In situ hybridization (ISH) f or IL-1 beta was performed using bone marrow aspirates from 51 MM, 7 smolde ring MM, 21 MGUS, and 5 normal control samples. Using the ISH technique IL- 1 beta mRNA was detectable in the plasma cells from 49 of 51 patients with active myeloma and 7 of 7 patients with smoldering myeloma. In contrast, 5 of 21 patients with MGUS and 0 of 5 normal controls had detectable IL-1 bet a message. Bone lesions were present in 40 of the 51 MM patients analyzed, and all 40 patients had IL-1 beta mRNA by ISH. These results show that grea ter than 95% of MM patients but less than 25% of MGUS patients are positive for IL-1 beta production. In the future, continued follow-up of IL-1 beta positive and negative MGUS patients should determine whether aberrant expre ssion of plasma cell IL-1 beta is predictive of those MGUS patients that wi ll eventually progress to active myeloma. (C) 1999 by The American Society of Hematology.