Endogenous monoclonal immunoglobulins analyzed using the EXENT? solution and LC-MS

Introduction: The EXENT (R) Solution, a fully automated system, is a recent advancement for identifying and quantifying monoclonal immunoglobulins in serum. It combines immunoprecipitation with MALDI-TOF mass spectrometry. Compared to gel -based methods, like SPEP and IFE, it has demonstrated the ability to detect monoclonal immunoglobulins in serum at lower levels. In this study, samples that tested negative using EXENT (R) were reflexed to LC -MS to determine if the more sensitive LC -MS method could identify monoclonal immunoglobulins missed by EXENT (R). Objectives: To assess whether monoclonal immunoglobulins that are not detected by EXENT (R) can be detected by LC -MS using a low flow LC system coupled to a Q-TOF mass spectrometer. Methods: Samples obtained from patients confirmed to have multiple myeloma (MM) were diluted with pooled polyclonal human serum and analyzed using EXENT (R). If a specific monoclonal immunoglobulin was not detected by EXENT (R), the sample was then subjected to analysis by LC -MS. For the LC -MS analysis, the sample eluate, obtained after the MALDI-TOF MS spotting step, was collected and transferred to an autosampler tray for subsequent analysis using LC -MS. Conclusion: LC -MS has the capability to detect monoclonal immunoglobulins that are no longer detected by EXENT (R). Reflexing samples to LC -MS for analysis does not involve additional sample handling, allowing for a faster time -to -result compared to current approaches, such as Next -Generation Sequencing, Next -Generation Flow, and clonotypic peptide methods. Notably, LC -MS offers equivalent sensitivity in detecting these specific monoclonal immunoglobulins.