PMC6308384_01
Bone marrow biopsy. Immunohistochemistry showing plasma cells staining for CD138 (a) and IgA (b) (original magnification x200 for [a] and x400 for [b]). The monoclonal plasma cells also showed kappa light chain restriction by in situ hybridization (not shown).
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The monoclonal plasma cells stained positive for IgA by immunohistochemistry (Figure 1).
Heavy chain deposition disease. [a,b] Nodular glomerulosclerosis with periodic acid-Schiff-positive, non-argyrophilic mesangial nodules ([a] periodic acid-Schiff, original magnification x200; [b] Jones methenamine silver, original magnification x200). [c-e] Negative routine immunofluorescence ([c] IgA, direct immunofluorescence, original magnification x100; [d] kappa light chain, direct immunofluorescence, original magnification x200; [e] lambda light chain, direct immunofluorescence, original magnification x200).
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The glomeruli showed moderate mesangial matrix expansion with frequent nodule formation, along with focal areas of segmental glomerulosclerosis (Figure 2a and b). All stains, including IgA, IgG, IgM, C3, C1q, fibrinogen, and kappa and lambda light chains, were negative within the glomeruli and throughout the tubulointerstitium (IgA, IgG, IgM, C3, C1q [Kent Laboratories, Bellingham, WA]; fibrinogen, kappa, and lambda [Agilent, Carpinteria, CA]) (Figure 2c-e).
Electron microscopy. Punctate-powdery deposits within the mesangium ([a] original magnification x8000) and tubular basement membranes ([b] original magnification x3000).
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Ultrastructural examination of a glomerulus showed marked mesangial matrix expansion by numerous punctate-powdery electron-dense deposits (Figure 3a). Similar deposits were present throughout the thickened tubular basement membranes (Figure 3b), and segmentally within the glomerular basement membranes.
Mass spectrometry. Scaffold software display of most abundant proteins and Ig-related proteins identified within the deposits by liquid chromatography/tandem mass spectrometry. The 2 columns on the right (LMD#1, LMD#2) represent the separate micro-dissected samples run in duplicate. The numbers within the columns represent the total number of mass spectra identified that correspond to the listed proteins on the left. The color of the box reflects the probability that the spectra are correctly assigned to the identified protein. In this case, there were abundant spectra for Ig alpha-1 chain constant region and apolipoprotein E, whereas insignificant numbers of spectra for serum amyloid P component, apolipoprotein A4, Ig lambda, Ig kappa, and Ig gamma were observed.
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Abundant spectra for Igalpha-1 chain C region (IgA1 constant region) and apolipoprotein E were detected (Figure 4).