Analysis of patients with γ-heavy chain disease by the heavy/light chain and free light chain assays.

BACKGROUND: The objective of this study was to evaluate the performance of the heavy/light chain and free light chain immunoassays in patients with heavy chain disease, and to assess the ability of the heavy/light chain assay to measure and confirm the abnormal, truncated heavy chain. METHODS: Frozen serum samples from 15 γ-heavy chain disease patients were tested for IgGκ, IgGλ, total IgG, free light chains, and M-spike concentrations. RESULTS: The (Gκ+Gλ)/IgGtotal ratio for these 15 patients ranged from 0.02 to 0.80. The 10 patients with IgG concentrations above 1 g/dL all had ratios below 0.3 indicating that a substantial portion of IgG was not quantitated by the Gκ and Gλ reagents. The average M-spike was 1.61 g/dL and the average calculated abnormal γ-chain concentration was 2.94 g/dL. Additionally, free light chain analysis revealed the presence of monoclonal free κ light chain in three of the 15 patients. CONCLUSIONS: This study demonstrates utility of a nephelometric assay to identify truncated immunoglobulin heavy chains in γ-HCD and that 20% of these patients also have monoclonal free light chain.

B-cell receptors and heavy chain diseases: guilty by association?

Heavy chain diseases (HCDs) are B-cell proliferative disorders characterized by the production of monoclonal, incomplete, immunoglobulin (Ig) heavy chains (HCs) without associated light chains (LCs). These abnormal HCs are produced as a consequence of HC gene alterations in the neoplastic B cells. HC gene alterations will also impact on surface HC, which is part of the B-cell receptor (BCR), a crucial player in lymphocyte activation by antigen. The selective advantage conferred to mutant cells by abnormal BCR without an antigen-binding domain may be explained by activation of ligand-independent signaling, in analogy to what has been shown for mutated oncogenic growth factor receptors. Here we review data obtained from mouse models showing abnormal, constitutive activity of HCD-BCR, and we discuss the possible mechanism involved, namely, aberrant spontaneous self-aggregation. This self-aggregation might occur as a consequence of escape from the chaperone immunoglobulin binding protein (BiP) and from the anti-aggregation effect of LC association. The concept of misfolding-induced signaling elaborated here may extend to other pathologies termed conformational diseases.

Ultrastructural immunolabeling in the diagnosis of monoclonal light-and heavy-chain-related renal diseases.

Renal dysfunction is often seen in patients with plasma cell dyscrasias. The abnormal light and heavy chains that are produced by the neoplastic plasma cells in these patients are responsible for the renal abnormalities that occur. The renal manifestations are heterogeneous and include alterations in all three renal compartments; sometimes more than one compartment is affected in a given case. It must be demonstrated that the renal abnormalities are directly related to the underlying plasma cell dyscrasia to make a definitive diagnosis of an associated lesion. Therefore, it becomes crucial to link the renal findings with the circulating nephrotoxic light or heavy chains. Immunofluorescence is very helpful and diagnostic in the majority of the cases, as it can localize the light or heavy chains to the various renal compartments showing alterations, and frequently confirm monoclonality. However, the antibodies that are used routinely do not necessarily label the abnormal light and heavy chains; the corollary of this is that a negative immunofluorescence workup does not rule out a light- or heavy-chain-related renal disorder. Electron microscopy is also important as it can depict crucial morphologic correlates to provide unique evidence or to simply confirm and clarify diagnostic findings. Ultrastructural immunolabeling combines the information obtained from immunofluorescence and electron microscopy by highlighting specific structures associated with the deposition of the pathogenic monotypical light and heavy chains.

Immunoglobulin M heavy chain disease: intracellular origin of the mu chain fragment.

Cells obtained from a patient with mu heavy chain disease synthesize a mu heavy chain fragment with a molecular weight of 55,000. The fragment is detected intracellularly after short labeling times and then is assembled inside the cell and secreted as a disulfide-linked polymer.

Absence of γ-Chain in Keratinocytes Alters Chemokine Secretion, Resulting in Reduced Immune Cell Recruitment.

Loss-of-function mutations in the common gamma (γc) chain cytokine receptor subunit give rise to severe combined immunodeficiency characterized by lack of T and natural killer cells and infant death from infection. Hematopoietic stem cell transplantation or gene therapy offer a cure, but despite successful replacement of lymphoid immune lineages, a long-term risk of severe cutaneous human papilloma virus infections persists, possibly related to persistent γc-deficiency in other cell types. Here we show that keratinocytes, the only cell type directly infected by human papilloma virus, express functional γc and its co-receptors. After stimulation with the γc-ligand IL-15, γc-deficient keratinocytes show significantly impaired secretion of specific chemokines including CXCL1, CXCL8, and CCL20, resulting in reduced chemotaxis of dendritic cells and CD4+ T cells. Furthermore, γc-deficient keratinocytes also exhibit defective induction of T-cell chemotaxis in a model of stable human papilloma virus-18 infection. These findings suggest that persistent γc-deficiency in keratinocytes alters immune cell recruitment to the skin, which may contribute to the development and persistence of warts in this condition and would require different treatment approaches.

Where disease pathogenesis meets protein formulation: renal deposition of immunoglobulin aggregates.

Aggregation is one of the important issues encountered during the development of immunoglobulin-based drugs. The aim of the current review is to discuss the causes and consequences of immunoglobulin aggregation as well as the relevance of immunoglobulin aggregation to disease pathogenesis. Extracellular deposition of immunoglobulins, either monoclonal light chains or intact polyclonal antibodies, induces renal failure in various nephropathies. The aggregates can present fibrillar or amorphous structures. In this review, factors known to influence protein aggregation, such as the primary structure of the protein, local environment and glycosylation are assessed, as well as the subsequent altered clearance, fibril formation and toxicity. The role of the protein local environment is emphasized. Even if the local environment causes only minor perturbations in the protein structure, these perturbations might be sufficient to trigger aggregate formation. This fact underlines the importance of choosing appropriate formulations for protein drugs. If the formulation provides a slightly destabilizing environment to the protein, the long-term stability of the drug may be compromised by aggregate formation.

The Expression Pattern of the Pre-B Cell Receptor Components Correlates with Cellular Stage and Clinical Outcome in Acute Lymphoblastic Leukemia.

Precursor-B cell receptor (pre-BCR) signaling represents a crucial checkpoint at the pre-B cell stage. Aberrant pre-BCR signaling is considered as a key factor for B-cell precursor acute lymphoblastic leukemia (BCP-ALL) development. BCP-ALL are believed to be arrested at the pre-BCR checkpoint independent of pre-BCR expression. However, the cellular stage at which BCP-ALL are arrested and whether this relates to expression of the pre-BCR components (IGHM, IGLL1 and VPREB1) is still unclear. Here, we show differential protein expression and copy number variation (CNV) patterns of the pre-BCR components in pediatric BCP-ALL. Moreover, analyzing six BCP-ALL data sets (n = 733), we demonstrate that TCF3-PBX1 ALL express high levels of IGHM, IGLL1 and VPREB1, and are arrested at the pre-B stage. By contrast, ETV6-RUNX1 ALL express low levels of IGHM or VPREB1, and are arrested at the pro-B stage. Irrespective of subtype, ALL with high levels of IGHM, IGLL1 and VPREB1 are arrested at the pre-B stage and correlate with good prognosis in high-risk pediatric BCP-ALL (n = 207). Our findings suggest that BCP-ALL are arrested at different cellular stages, which relates to the expression pattern of the pre-BCR components that could serve as prognostic markers for high-risk pediatric BCP-ALL patients.

A case of monoclonal immunoglobulin light- and heavy-chain deposition disease exhibiting atypical deposition with fibrillary structures, successfully treated with chemotherapy.

We report a case of light and heavy chain deposition disease (LHCDD), a rather rare monoclonal immunoglobulin deposition disease (MIDD) with successful therapeutic effect. A 58-year-old woman suffered from proteinuria and renal insufficiency (serum creatinine 1.0 mg/dl, creatinine clearance 49.2 ml/min) in February 2003. In serum and urine samples, monoclonal IgG-kappa was detected. A bone marrow aspiration showed a slightly hypocellular marrow and plasma cell population was increased to 7.0%. Renal histological findings revealed lobulated glomeruli with nodular lesions on light microscopy, characteristic findings of MIDD. Intense deposition of IgG heavy chains in the linear pattern in the glomerular and tubular basement membranes was observed. Immunohistochemistry revealed both kappa and lambda light chain depositions in glomeruli. Electron-microscopic examination revealed fine granular electron-dense deposits accompanied by microfibrils. Based on these findings, this patient was diagnosed as LHCDD. She received three courses of melphalan and prednisone chemotherapy, resulting in disappearance of proteinuria, prevention of renal functional deterioration and the decrease of monoclonal immunoglobulin. This case clearly demonstrates that the earlier and accurate diagnosis and initiation of chemotherapy at the early stage with serum creatinine level below 4.0 mg/dl are necessary to improve renal and patient outcome.

Metachronous development of nonamyloidogenic [lambda] light chain deposition disease and IgG heavy chain amyloidosis in the same patient.

We report a highly unusual case of monoclonal immunoglobulin deposition disease-associated nephrotic syndrome in which a patient developed both lambda light chain deposition disease and 6 years afterward IgG-heavy chain amyloidosis. The patient initially underwent autologous peripheral blood stem cell transplantation as treatment of the underlying plasma cell dyscrasia causing the light chain deposition disease-related nephrotic syndrome. After 6 years of clinical remission, recurrence of the nephrotic syndrome led to a renal biopsy demonstrating IgG-heavy chain amyloidosis. Interestingly, much of the characteristic nodular glomerular sclerosis seen in light chain deposition disease regressed between the time of the first biopsy and the second. Given the length of time between the development of the two diseases and the apparent success of stem cell transplantation in treating the first, we think that the patient produced two distinctly different abnormal plasma cell clones. To our knowledge, this is the first report of two different monoclonal immunoglobulin deposition diseases occurring in the same patient.

Nodular glomerulosclerosis secondary to mu heavy chain deposits.

mu heavy chain deposition disease is very rare. We report the first case of glomerulonephritis in a woman without evidence of hematopoietic malignancy. Nodular glomerulosclerosis and monotypic mu heavy chain mesangial deposits were identified by immunofluorescence without kappa or lambda deposits. Electron microscopy showed fibrillar mesangial deposits of 16-18 nm in diameter. Serum immunoglobulins, cryoglobulins, serum immunoelectrophoresis, and immunofixation, bone marrow biopsy, and Bence Jones proteins in urine were negative. The patient has stable renal disease and is free of malignancy 6 years after the initial occurrence of proteinuria.

Abnormal immunoglobulin synthesis in monoclonal immunoglobulin light chain and light and heavy chain deposition disease.

The Congo red-binding fibrils of AL amyloidosis are the most common form of monoclonal immunoglobulin tissue deposition (MIDD). Nonetheless, the less structured deposits found in light chain deposition disease (LCDD) and the similar, but distinct, deposits of light and heavy chain deposition disease (LHCDD) and heavy chain deposition disease (HCDD) can produce significant clinical pathology. Analyses of immunoglobulin synthesis by bone marrow cells obtained from 7 patients with LCDD and LHCDD demonstrated the production of excess light chains in all and the presence of incomplete light chains or heavy chain fragments in 5, regardless of the presence of an intact monoclonal protein or related subunit in the serum or urine. Our data indicate that, as is the case with the fibrillar deposits of AL amyloid, the non-fibrillar forms of monoclonal Ig deposition (LCDD and LHCDD) can be associated with the presence of immunoglobulin fragments in bone marrow cells. In some instances these appeared to be synthetic in origin, although rapid intracellular proteolysis or a combination of both could not be excluded. In either case the fragments may be more susceptible to tissue deposition, with subsequent organ compromise, than intact Ig chains.

Gamma-heavy chain deposition disease showing nodular glomerulosclerosis.

We describe a 35-year-old woman who had nodular glomerulosclerosis associated with deposition of fragmented gamma (gamma 1)-heavy chains. She presented with edema of lower legs, mild proteinuria, and hematuria. Laboratory examination revealed hypocomplementemia, and a small amount of monoclonal IgG-lambda (lambda) in the blood. Renal biopsy disclosed prominent nodular expansion of the mesangium. Ultrastructurally, the nodules were composed of electron dense deposits and fibrillar structures. An immunofluorescent study showed depositions of gamma-heavy chains and C3 in the central portion of nodules and capillary walls, whereas kappa (kappa)-, lambda-light chains, and Fab fragments of the heavy chain were negative. The accumulation of collagen I, IV, V, and VI was demonstrated in the mesangium. Western blot analysis of serum protein disclosed fragmented gamma-heavy chains that did not combine with light chains. Glomerular nodular lesions, thus, can occur in heavy chain deposition disease, as in light chain deposition disease. Fragmented gamma-heavy chains may also induce hypocomplementemia by the activation of the complement pathway.

Cast nephropathy in mu heavy chain disease.

The occurrence of kidney diseases was very rarely reported in heavy chain diseases (HCD). At variance with gamma and alpha HCD in which there is no free light chain secretion, about two-thirds of mu HCD patients have urinary Bence Jones (BJ) proteins. We report on a 66 year-old man affected with typical mu HCD who developed renal failure after a 3-year follow-up. He had presented with chronic lymphocytic leukemia with bone marrow vacuolated plasma cells, serum mu HCD protein and serum and urine BJ protein. After an apparent hematological remission following fludarabine therapy, anemia and blood hyperlymphocytosis recurred together with microscopic hematuria, proteinuria and increased creatininemia. Kidney biopsy showed numerous tubular eosinophilic casts which stained for kappa chain determinants by immunofluorescence and an interstitial infiltration by lymphocytes and plasma cells. The hematological and renal condition improved after reinitiation of chemotherapy. This appears to be the first documented report of a light chain-dependent visceral complication in HCD.

Further studies on an eleventh case of heavy (Hgamma1) chain disease--clinical studies.

An eleventh case of heavy (Hgamma1) chain disease (Yok), surviving for more than 10 years and still living showed clinical and pathological findings similar to cases described in the past. The patient was given only glucocorticosteroids, ACTH, antibiotics and gamma globulin, as specific drugs. Precipitation arcs besides the major ones formed by albumin and Fc fragment were disclosed by immunoelectrophoresis. The existence of these minor components were confirmed with antigen-antibody crossed electrophoresis and Sephadex G-200 gel filtration. They did not form precipitation arcs with the other antigens available and they appeared in the same fractions of IgG on gel filtration suggesting their having higher molecular weight than the major ones. In addition to these findings, the clinical course of the patient is described.

Further studies on an eleventh case of heavy (Hgamma1) chain disease--physico-chemical studies.

An abnormal protein with similar antigenic properties to Fc fragments of IgG, was found in the serum and urine of an eleventh case of heavy (Hgamma1) chain disease (Yok). This protein was purified with ammonium sulfate precipitation and by column chromatography of DEAE cellulose, CM cellulose and Sephadex G-200. The purity of the protein obtained was 98.5%. It was crystallized easily, forming thin hexagonal plates of various sizes. The chemical compositions and physical properties of the protein including viscosity, partial specific volume, diffusion constant, sedimentation constant, frictional ratio, extinction coefficient and iso-ionic point are reported.

Further studies on an eleventh case of heavy (Hgamma1) chain disease--biosynthetic studies.

In vitro quantitative biosynthetic studies were carried out on bone marrow cells obtained from an eleventh case with gamma heavy chain disease. The findings indicate that neither cytoplasmic nor extracellular degradation was responsible for the presence of the gamma heavy chain fragment in serum. The absence of a covalent-bound light chain was also confirmed.

[A case report of light and heavy chain deposition disease (IgG2 lambda)].

A 73-year-old male was admitted to the renal division of our hospital because of hypertension, proteinuria and bilateral pretibial edema. Eight years previously, he was diagnosed as being afflicted with interstitial pneumonia on the basis of a chest X-ray examination. Laboratory tests conducted during the current admission showed normocytic normochromic anemia, renal dysfunction and mild proteinuria. Total IgG was normal, but a high proportion of IgG2 was observed. M-protein in the serum was positive for both IgG lambda and Bence Jones protein (lambda type). A bone marrow biopsy showed the proportion of plasma cells to be 10.6%, but atypical cells were not found. We diagnosed the patient's condition as plasma cell dyscrasia. Light microscopy examination of a renal biopsy specimen showed moderate mesangial proliferation with a deposition of PAS-positive and Congo red negative materials in the mesangial area: nodular gomerulonephritis was seen in some glomeruli. Immunofluorescence revealed IgG and lambda light chains, strong linear staining along the glomerular basement membrane and tubular basement membrane and positivity in the mesangial area. Results of staining for IgA, IgM, fibrinogen and C3 were weakly positive in the mesangium area, while those for C4, Clq and free kappa were negative. Positive staining of IgG2 was seen by immunoperoxidase study, but the tissue was negative for IgG1, IgG3, IgG4. Electron microscopy demonstrated a dense granular deposition in the mesangial, subendothelial and peritubular area and a microfibrillar structure in the mesangial area. The diameter of the microfibrillar structure was 14 nm on the average.(ABSTRACT TRUNCATED AT 250 WORDS)