The amino acid sequence of a monoclonal gamma 3-heavy chain from a patient with articular gamma-heavy chain deposition disease

Heavy-chain deposition disease: a morphological, immunofluorescence and ultrastructural assessment

Heavy-chain deposition disease (HCDD) is the least common of the monoclonal immunoglobulin deposition diseases with only 24 reported cases in English literature, including the present case. The rarity of this disease merits its documentation. We present a case of HCDD from our archival material, who presented with rapidly progressive renal failure and nephrotic syndrome and was found to have nodular glomerulosclerosis on renal biopsy which on immunofluorescence and electron microscopy confirmed HCDD of immunoglobulin G1 type without any light-chain deposition. We also present an in-depth literature review on HCDD.

Gamma heavy chain disease in a patient with diabetes and chronic renal insufficiency: diagnostic assessment of the heavy chain fragment

Heavy chain diseases are rare B-cell disorders that are characterized by an overproduction of abnormal and structurally incomplete monoclonal immunoglobulin (Ig) heavy chains and are devoid of light chains. We describe a case of a 62 year-old African-American woman with a long history of poorly controlled type 2 diabetes and subsequent probable diabetic nephropathy, hypertension, and recent onset of peripheral neuropathy involving all extremities. Routine laboratory testing revealed a distinct beta spike by urine protein electrophoresis (UPEP). No serum abnormality was noted on serum protein electrophoresis (SPEP). Serum and urine immunofixation demonstrated an IgG heavy chain protein devoid of any corresponding light chains. IgG subclasses identified IgG1 as the predominant IgG component but when we added all the subclasses, the sum, 683.4 mg/dL, failed to come close to our total IgG of 1,770 mg/dL. Therefore, a urine IgG subclass determination was performed in-house and we identified a subclass 3 gamma chain. In conclusion, we portray a patient with an underlying monoclonal gamma heavy chain disease (HCD) who presented with a complex medical history. The evaluation of IgG subclasses in the context of a HCD may be limited by the capability of the test to recognize the particular IgG fragment.

Glycan analysis of monoclonal antibodies secreted in deposition disorders indicates that subsets of plasma cells differentially process IgG glycans

OBJECTIVE

To compare the glycosylation of polyclonal serum IgG heavy chains in a patient with rheumatoid arthritis (RA) with that of monoclonal serum IgG heavy chains in the same patient during an episode of heavy-chain deposition disease (HCDD), to establish whether glycosylation processing is specific for subsets of B cells.

METHODS

Serum IgG was purified using a HiTrap protein G column. Immunoglobulins were run on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels, and IgG glycans were isolated from gel bands and fluorescently labeled. Glycans were analyzed by normal-phase high-performance liquid chromatography and by liquid chromatography-electrospray ionization-mass spectrometry.

RESULTS

The glycosylation of serum immunoglobulins from a patient with seronegative RA and HCDD was analyzed. The predominant immunoglobulin was a truncated glycosylated gamma3 heavy chain, and a small amount of polyclonal IgG was also present. The glycan profile showed that the monoclonal gamma3 heavy chain contained fully galactosylated biantennary glycans with significantly less fucose but more sialic acid than in IgG3 from healthy controls. In contrast, the polyclonal IgG showed an RA-like profile, with a predominance of fucosylated biantennary glycans and low levels of galactosylation. The glycan profile of serum IgG obtained from the same patient during disease remission resembled a typical RA profile.

CONCLUSION

These data indicate that different types of B cells process a particular set of IgG glycoforms.

A patient with severe renal amyloidosis associated with an immunoglobulin γ-heavy chain fragment

The authors report a patient with progressive renal dysfunction caused by severe renal amyloidosis associated with a gamma-heavy chain variable region (V(H)) fragment. The patient was a 71-year-old woman who had renal insufficiency without nephrotic syndrome. Laboratory data showed a monoclonal IgG lambda component in her serum and urine. Renal biopsy results showed massive amyloid deposition in the mesangial region, but the glomerular basement membranes and epithelial cells were preserved. Because immunohistochemical studies using antibodies against a number of known amyloid fibril proteins failed to detect the amyloid protein, the amyloid protein extracted from a small piece of the biopsied renal tissue was subjected to biochemical analysis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the extracted amyloid protein showed a prominent band at 11-kDa, and this protein was identified by amino acid sequence analysis as a gamma-heavy chain variable region fragment (V(H)3 subgroup) without the first N-terminal residue. Our results indicate that the patient's renal amyloidosis was associated with a gamma-heavy chain variable region fragment. Microextraction and biochemical characterization of amyloid fibrils was of great use for reaching a definitive diagnosis.

Immunoglobulin γ3-heavy-chain deposition disease: report of a case and relationship with hypocomplementemia

The authors describe a 54-year-old woman presenting with proteinuria, hematuria, and hypocomplementemia whose renal biopsy results showed diffuse increase in mesangial matrix and nodular formations in several glomeruli with the deposition of immunoglobulin gamma3-heavy-chain and complement components C1q and C3 in the glomeruli and on the tubular basement membranes, without associated light-chain deposits. Staining for the constant domains of gamma-heavy-chain showed a deletion of the first constant domain (CH1). These findings were consistent with those of gamma-heavy-chain deposition disease (gamma-HCDD). The patient was treated monthly with melphalan and prednisolone although a bone marrow aspirate did not show findings suggestive of plasmacytoma. Six courses of melphalan and prednisolone therapy resulted in a marked reduction of urinary protein excretion and marked rise of complement levels. The current case is the fourth HCDD patient reported featuring gamma3-heavy-chain deposition who showed severe hypocomplementemia and responded to chemotherapy with improved renal parameters and complement levels. A review of previously reported cases of HCDD showed that some but not all HCDD cases were associated with hypocomplementemia. The authors also discuss here the relationship of HCDD to hypocomplementemia.

Articular, monoclonal gamma3 heavy-chain deposition disease: characterization of a partially deleted heavy-chain gene and its protein product synthesized in vivo and in vitro

OBJECTIVE

A patient presented with heavy-chain deposition disease (HCDD), exhibiting severe erosive polyarthropathy caused by synovial deposits of abnormal monoclonal, heavily deleted free gamma3 heavy chains lacking the V(H) and C(H)1 domains. The absence of V(H) was surprising, since it is considered important for pathogenic tissue deposition. This study was undertaken to analyze the genetic structure of the heavy chain, the protein product synthesized in vitro, and that deposited in the synovium in comparison with the serum and urinary proteins.

METHODS

Hybridomas were made by fusion of blood and bone marrow mononuclear cells with mouse myeloma cells. Cloned B cell hybridomas secreting gamma3 were selected and analyzed by polymerase chain reaction. Purified hybridoma Ig was sequenced by Edman degradation. Antiserum raised to a peptide corresponding to residues 2-15 of the truncated V(H) was used in Western blots of synovial tissue.

RESULTS

The hybridomas secreted free gamma3 chains consisting of a V(H)4 gene truncated 21 nucleotides into the first complementarity-determining region and then reading straight into the hinge region. The amino acid sequence confirmed the presence of residues 1-32 of the V(H)4 gene. Immunoblotting of synovial tissue showed the presence of Ig with truncated V(H).

CONCLUSION

The gamma3 heavy chain had a deletion of V(H) from codon 33 and of the entire C(H)1. In vivo, the 32 V(H) amino acids were proteolytically degraded. In the joint, however, the 32 residues of V(H) remained intact, consistent with a pathogenic role of V(H) for tissue deposition. To our knowledge, this is the first reported case of gammaHCDD causing an erosive, polyarticular arthropathy as the dominating clinical feature.