Evaluation of interleukin-18 levels in patients affected by multiple myeloma and monoclonal gammopathy of undetermined significance: analysis and review of the literature.

Monoclonal gammopathy of undetermined significance (MGUS) is a preneoplastic disease that often precedes multiple myeloma. The multistep evolutionary pattern of multiple myeloma is driven by genetic instability, a pro-inflammatory and immunosuppressive microenvironment, and tumor growth. Inflammation has long been recognized as a factor in both the onset and progression of cancer. In this study, interleukin-18 plasma levels were compared in patients with multiple myeloma and monoclonal gammopathy of undetermined significance, as well as in a group of healthy controls. Our study shows that monoclonal gammopathy of undetermined significance patients have lower levels of interleukin-18 than healthy controls (521.657 ± 168.493 pg/ml vs. 1,266.481 ± 658.091 pg/ml for controls, p < 0.001). Thus, we discovered a significant difference in interleukin-18 levels between multiple myeloma patients and controls (418.177 ± 197.837 pg/ml; p = 0.001). In our work, we identified a reduction of interleukin-18 in monoclonal gammopathies. Furthermore, in this paper, we aimed to evaluate the existing literature on the potential mechanisms of action of this pro-inflammatory cytokine in the development of these diseases.