Expression of the IL-6 receptor alpha-chain (CD126) in normal and abnormal plasma cells in monoclonal gammopathy of undetermined significance and smoldering myeloma

Abstract

IL-6 activity in normal plasma cells (nPCs) and abnormal plasma cells (aPCs) is CD126 (subunit of IL-6 receptor) dependent. We quantified CD126 expression on nPCs and aPCs in monoclonal gammopathy of undetermined significance (MGUS), smoldering myeloma (SMM), and multiple myeloma (MM). CD126 was detected on all nPCs and aPCs indicating that CD126 does not have diagnostic utility. CD126 expression was higher in aPCs than in nPCs in 85% SMM but only 41% MGUS and there was evidence that CD126 was higher in aPCs than nPCs in the SMM (p = .048) but not MGUS (p = .96) patients. There is also a greater association between nPC and aPC CD126 expression in low risk MGUS than observed in high risk MGUS and SMM, suggesting normal regulation of CD126 decreases with disease progression. Future studies need to elucidate the role of bone marrow milieu versus escape from normal CD126 regulation in malignant transformation of clonal plasma cells.

Keywords:

• MGUS
• smoldering myeloma
• IL-6 receptor
• CD126
• flow cytometry

Potential conflict of interest

Disclosure forms provided by the authors are available with the full text of this article online at https://doi.org/10.1080/10428194.2017.1321746.

Additional information

Funding

This research was funded by intramural program of Center for Cancer Research, NCI, NIH.