Figure 1.

PSM Matches From LC-MS/MS Analysis of Endomyocardial Biopsy From Case 2

Protein spectrum matches (PSM) convey information on the relative abundance of particular proteins. In most cases of amyloid, a few proteins are always identified and in relatively abundant quantities: serum P component, apolipoprotein E, apolipoprotein A1, apolipoprotein AIV, and vitronectin (yellow). Further examination identifies multiple proteins with amyloidogenic properties, including transthyretin (green) and the immunoglobulin light chains (red). The identification of transthyretin in the samples, at a PSM comparable to that of the other amyloid-associated proteins, is evidence that the amyloid has a significant transthyretin component. Immunoglobulin heavy and light chains are present in virtually all patient samples, a consequence of serum contamination. However, in this case, the light chains are present at concentrations similar to those of other amyloid-associated proteins. Although kappa immunoglobulin light chains are significantly more abundant than lambda in most patients, in this case, lambda light chains dominated, providing another piece of evidence that amyloid has a significant lambda light chain component. PSM duplicates 1 and 2 represent duplicate testing results from the same patient. LC-MS/MS = liquid chromatography with tandem mass spectrometry.