In the May issue of Clinical Chemistry, David Murray, Ph.D., of the Mayo Clinic, analyzed the measurement of IgG subclasses in the article, "Quantification of Serum IgG Subclasses by Use of Subclass-Specific Tryptic Peptides and Liquid Chromatography–Tandem Mass Spectrometry."
Dr. Murray and his colleagues combined serum with labeled internal peptide standards and intact purified horse IgG. The samples were then denatured, reduced, alkylated and digested. The group analyzed the digested serum by LC-MS/MS for IgG subclasses 1–4 and total IgG.
Upon assaying 112 patient sera by LC-MS/MS and immunonephelometry, it was discovered that total IgG and IgG subclasses 1, 2, 3, and 4 can be quantified by LC-MS/MS with performance comparable to nephelometry.