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

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Mass Spectrometry

Background:

• The EXENT® Solution is an automated system for identifying and quantifying monoclonal immunoglobulins in serum, combining immunoprecipitation with MALDI-TOF mass spectrometry.
• EXENT® demonstrates improved sensitivity over traditional gel-based methods like SPEP and IFE for detecting monoclonal immunoglobulins.
• The clinical significance of monoclonal immunoglobulins necessitates sensitive and accurate detection methods.

Purpose of the Study:

• To evaluate the capability of liquid chromatography-mass spectrometry (LC-MS) to detect monoclonal immunoglobulins that are not identified by the EXENT® Solution.
• To assess the feasibility of using LC-MS as a reflex test for samples negative by EXENT®.

Main Methods:

• Serum samples from patients with multiple myeloma (MM) were analyzed using the EXENT® Solution.
• Samples negative for monoclonal immunoglobulins by EXENT® were subsequently analyzed by LC-MS.
• LC-MS analysis utilized eluate from the MALDI-TOF MS spotting step, employing a low-flow LC system coupled to a Q-TOF mass spectrometer.

Main Results:

• LC-MS successfully detected monoclonal immunoglobulins in samples that tested negative by the EXENT® Solution.
• The study confirmed that LC-MS offers equivalent sensitivity to EXENT® for detecting these specific monoclonal immunoglobulins.

Conclusions:

• Reflexing samples to LC-MS for analysis is a viable strategy to identify monoclonal immunoglobulins potentially missed by EXENT®.
• This approach streamlines workflow, avoiding additional sample handling and enabling a faster time-to-result compared to other advanced methods.
• LC-MS provides a sensitive and efficient complementary method for monoclonal immunoglobulin detection in clinical diagnostics.