Simultaneous quantification of plasma immunoglobulin subclasses for assessment of maternal and fetal immune response...

Measurement of immunoglobulin subclasses is a useful tool for exploring humoral immune deficiency in the presence of total immunoglobulins within reference intervals. Conventional methods for immunoglobulin measurement are mostly immunoassays, which are of low throughput and laborious to run multiple immunoglobulin subclass tests. Liquid chromatography-mass spectrometry (LC-MS) has emerged as a promising technology for the measurement of protein biomarkers in biological matrices, owing to its high specificity, selectivity, multiplexing, and wide dynamic range. In fully taking these advantages, we developed here a LC-MS based methodology for simultaneous quantitation of the primary immunoglobulin isotypes (IgG, IgA, IgM) and their subclasses in human plasma. Method validation demonstrated that the proposed method showed good linearity with R > 0.99, high precision with coefficients of variation for inter- and intra-assay less than 15%, as well as high accuracy with relative errors less than 8.7%. The developed method was further applied to maternal and cord blood collected at delivery for assessment of maternal and fetal immune status. The immunoglobulin profiles and the features of transplacental transport of maternal immunoglobulin subclasses were comparable to the findings from previous reports, further demonstrating the reliability of this method. Therefore, our method provides a competitive approach to high-throughput detection of multiple immunoglobulin subclasses for biomonitoring or epidemiological studies.