Alladi Ramakrishnan Hall

MALDI-TOF Mass Spectrometry for M-protein Analysis: From Bench to Bedside

Nikita Mehra

Cancer Institute W.I.A, Chennai

Monoclonal gammopathy of undetermined significance (MGUS), multiple myeloma (MM), plasmacytoma(s), light chain (AL) amyloidosis and Waldenström macroglobulinemia belong to a group of disorders known as clonal plasma cell dyscrasias. MM is the second most common hematological malignancy in the elderly and is preceded by an asymptomatic state known as MGUS. These disorders are diagnosed by detecting abnormally secreted M-protein in the blood, and sometimes in the urine. M-protein is analyzed by a multitude of tests, including serum/urine protein electrophoresis (SPEP/ UPEP), serum/urine immunofixation (IFE) and serum/urine free light chains (sFLC/uFLC). The combination of these tests can be laborious, time-consuming, and expensive. We report the results of a novel, low-cost, reagent-based extraction process using acetonitrile (ACN) precipitation to enrich for κ and λ light chains which can be analysed by MALDI-TOF MS. Compared to IFE which is the gold standard for M-protein detection, the sensitivity and specificity of M-protein identification by MALDI-TOF MS using acetonitrile precipitation was 98.3% and 52.2%, respectively. We are presently validating the technique on 3500 serum samples as a part of an ongoing epidemiology study in Tamil Nadu.