Heavy-chain diseases

A Recombinant Ig Fragment (IgCw-γεκ) Comprising the Cγ1-Cε2-4 and Cκ Domains Is an Alternative Reagent to Human IgE

Human IgE is useful for immunological assays, such as sensitization of FcεRI-positive cells and IgE measurement. In this study, we report the development of a recombinant Ig fragment, designated IgCw-γεκ, as an alternative reagent to human IgE. IgCw-γεκ (∼130 kDa) comprises two hybrid constant H chain regions (Cγ₁-Cε_2-4, each ∼53 kDa) and two constant κ L chains (C_κ, each ∼12 kDa) and lacks a V domain. The presence of Cγ₁ instead of Cε₁ within the H chain increased the production yield and facilitated assembly of the H and L chains. IgCw-γεκ was produced in cultured human embryonic kidney 293F cells, with a yield of ∼27 mg/l. IgCw-γεκ bound to human FcεRIαRs expressed on the surface of rat basophilic leukemia-2H3 cells. A β-hexosaminidase release assay revealed that the biological activity of IgCw-γεκ was comparable with that of IgE. The IgE concentration measured using IgCw-γεκ as a standard was similar to that measured using IgE as a standard. These results suggest that the IgCw-γεκ molecule retains the basic characteristics of IgE, but does not cross-react with Ags, making it an alternative to the IgE isotype references used in a variety of immunological assays.

Heavy Chain Disease of the Small Bowel

PURPOSE OF REVIEW

The purpose of this review is to discuss current knowledge and recent findings regarding pathogenesis, outcome, and treatment for heavy chain disease (HCD) involving the small bowel, focusing on alpha HCD or immunoproliferative small intestinal disease (IPSID), the HCD subtype typically affecting the small bowel.

RECENT FINDINGS

A link between Campylobacter jejuni infection and IPSID has been established, but there is controversy as to the role played by this organism in disease pathogenesis. While cytogenetic abnormalities involving various immunoglobulin loci and PAX5 have been reported, these have been described in rare, single cases, limiting their ability to shed further light on disease pathogenesis. IPSID is typically regarded as a pre-lymphomatous condition with eventual progression to frank lymphoma; however, recent reports of longstanding non-progressive cases have expanded its clinical spectrum. IPSID is an uncommon disorder affecting the small intestine. This review focuses on current knowledge and novel insight regarding its pathogenesis, outcome, and treatment, with an emphasis on future directions.

Heavy-Chain Diseases and Myeloma-Associated Fanconi Syndrome: an Update

The heavy chain diseases (HCDs) are rare B-cell malignancies characterized by the production of a monoclonal immunoglobulin heavy chain without an associated light chain. There are three types of HCD, defined by the class of immunoglobulin heavy chain produced: IgA (α-HCD), IgG (γ-HCD), and IgM (μ-HCD). Alpha-HCD is the most common and usually occurs as intestinal malabsorption in a young adult from a country of the Mediterranean area. Gamma- and μ-HCDs are rarer and associated with a B-cell non-Hodgkin lymphoma that produces an abnormal Ig heavy chain. These patients may occasionally be diagnosed with a monoclonal gammopathy of undetermined significance (MGUS). Fanconi syndrome, on the other hand, can be primary (inherited) or secondary (acquired). The only exception to this rule is the idiopathic form. Adult acquired Fanconi syndrome can be a rare complication of a monoclonal gammopathy. At diagnosis, most patients have an MGUS or smoldering multiple myeloma, with renal failure and evidence of osteomalacia. During follow-up, patients can develop an end-stage renal disease. Chemotherapy provides little benefit on renal function.

Roles of N-glycans in the polymerization-dependent aggregation of mutant Ig-μ chains in the early secretory pathway

The polymeric structure of secretory IgM allows efficient antigen binding and complement fixation. The available structural models place the N-glycans bound to asparagines 402 and 563 of Ig-μ chains within a densely packed core of native IgM. These glycans are found in the high mannose state also in secreted IgM, suggesting that polymerization hinders them to Golgi processing enzymes. Their absence alters polymerization. Here we investigate their role following the fate of aggregation-prone mutant μ chains lacking the Cμ1 domain (μ∆). Our data reveal that μ∆ lacking 563 glycans (μ∆5) form larger intracellular aggregates than μ∆ and are not secreted. Like μ∆, they sequester ERGIC-53, a lectin previously shown to promote polymerization. In contrast, μ∆ lacking 402 glycans (μ∆4) remain detergent soluble and accumulate in the ER, as does a double mutant devoid of both (μ∆4–5). These results suggest that the two C-terminal Ig-μ glycans shape the polymerization-dependent aggregation by engaging lectins and acting as spacers in the alignment of individual IgM subunits in native polymers.

Biochemical nature of Russell Bodies

Professional secretory cells produce and release abundant proteins. Particularly in case of mutations and/or insufficient chaperoning, these can aggregate and become toxic within or amongst cells. Immunoglobulins (Ig) are no exception. In the extracellular space, certain Ig-L chains form fibrils causing systemic amyloidosis. On the other hand, Ig variants lacking the first constant domain condense in dilated cisternae of the early secretory compartment, called Russell Bodies (RB), frequently observed in plasma cell dyscrasias, autoimmune diseases and chronic infections. RB biogenesis can be recapitulated in lymphoid and non-lymphoid cells by expressing mutant Ig-μ, providing powerful models to investigate the pathophysiology of endoplasmic reticulum storage disorders. Here we analyze the aggregation propensity and the biochemical features of the intra- and extra-cellular Ig deposits in human cells, revealing β-aggregated features for RB.

Kidney diseases associated with monoclonal immunoglobulin M-secreting B-cell lymphoproliferative disorders: a case series of 35 patients

BACKGROUND

Kidney diseases associated with immunoglobulin M (IgM) monoclonal gammopathy are poorly described, with few data for patient outcomes and renal response.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

35 patients from 8 French departments of nephrology were retrospectively studied. Inclusion criteria were: (1) detectable serum monoclonal IgM, (2) estimated glomerular filtration rate (eGFR) < 60mL/min/1.73m(2) and/or proteinuria with protein excretion > 0.5g/d and/or microscopic hematuria, and (3) kidney biopsy showing monoclonal immunoglobulin deposits and/or lymphomatous B-cell renal infiltration. All patients received chemotherapy, including rituximab-based regimens in 8 cases.

PREDICTORS

Patients were classified into 3 groups according to renal pathology: glomerular AL amyloidosis (group 1; n=11), nonamyloid glomerulopathies (group 2; n=15, including 9 patients with membranoproliferative glomerulonephritis), and tubulointerstitial nephropathies (group 3; n=9, including cast nephropathy in 5, light-chain Fanconi syndrome in 3, and isolated tumor infiltration in 1).

OUTCOMES

Posttreatment hematologic response (≥50% reduction in serum monoclonal IgM and/or free light chain level) and renal response (≥50% reduction in 24-hour proteinuria or eGFR≥30mL/min/1.73m(2) in patients with glomerular and tubulointerstitial disorders, respectively).

RESULTS

Nephrotic syndrome was observed in 11 and 6 patients in groups 1 and 2, respectively. Patients in group 3 presented with acute kidney injury (n=7) and/or proximal tubular dysfunction (n=3). Waldenström macroglobulinemia was present in 26 patients (8, 12, and 6 in groups 1, 2, and 3, respectively). Significant lymphomatous interstitial infiltration was observed in 18 patients (4, 9, and 5 patients, respectively). Only 9 of 29 evaluable patients had systemic signs of symptomatic hematologic disease (2, 5, and 2, respectively). In groups 1, 2, and 3, respectively, hematologic response was achieved after first-line treatment in 3 of 9, 9 of 10, and 5 of 6 evaluable patients, while renal response occurred in 5 of 10, 9 of 15, and 5 of 8 evaluable patients.

LIMITATIONS

Retrospective study; insufficient population to establish the impact of chemotherapy.

CONCLUSIONS

IgM monoclonal gammopathy is associated with a wide spectrum of renal manifestations, with an under-recognized frequency of tubulointerstitial disorders.

Gamma heavy-chain disease: defining the spectrum of associated lymphoproliferative disorders through analysis of 13 cases

Gamma heavy-chain disease (gHCD) is defined as a lymphoplasmacytic neoplasm that produces an abnormally truncated immunoglobulin gamma heavy-chain protein that lacks associated light chains. There is scant information in the literature regarding the morphologic findings in this rare disorder, but cases have often been reported to resemble lymphoplasmacytic lymphoma (LPL). To clarify the spectrum of lymphoproliferative disorders that may be associated with gHCD, this study reports the clinical, morphologic, and phenotypic findings in 13 cases of gHCD involving lymph nodes (n=7), spleen (n=2), bone marrow (n=8), or other extranodal tissue biopsies (n=3). Clinically, patients showed a female predominance (85%) with frequent occurrence of autoimmune disease (69%). Histologically, 8 cases (61%) contained a morphologically similar neoplasm of small lymphocytes, plasmacytoid lymphocytes, and plasma cells that was difficult to classify with certainty, whereas the remaining 5 cases (39%) showed the typical features of one of several other well-defined entities in the 2008 WHO classification. This report demonstrates that gHCD is associated with a variety of underlying lymphoproliferative disorders but most often shows features that overlap with cases previously reported as "vaguely nodular, polymorphous" LPL. These findings also provide practical guidance for the routine evaluation of small B-cell neoplasms with plasmacytic differentiation that could represent a heavy-chain disease and give suggestions for an improved approach to the WHO classification of gHCD.

T/NK large granular lymphocyte leukemia and coexisting monoclonal B-cell lymphocytosis-like proliferations. An unrecognized and frequent association

T-cell large granular lymphocyte leukemia (T-LGLL) is a T-cell lymphoproliferative disorder that has recently been associated with B-cell dyscrasias on a spectrum ranging from dysgammaglobulinemia to lymphoma. To investigate the relationship between clonal B-cell and LGLL lymphoproliferations, we systematically studied lymphocytes in 57 patients with T-LGLL or NK lymphocytosis using flow cytometric methods sensitive to low-level B-cell populations. We identified 16 patients (28%) with abnormal B-cell populations; 9 (16%) of the patients had no known history of a B-cell lymphoproliferative disorder. We characterized these abnormal B-cell populations as monoclonal B-cell lymphocytosis and report a high frequency of monoclonal B-cell lymphocytosis in T/NK LGLL. Our findings suggest that certain pathologic factors may operate in patients with T/NK LGLL to drive low-level clonal B-cell proliferations.

Multiple myeloma and immunosecretory disorders: an update

The immunosecretory disorders are a diverse group of diseases associated with proliferation of an abnormal clone of immunoglobulin (Ig)-synthesizing, terminally differentiated B cells. These disorders include multiple myeloma (MM) and its variants, plasmacytoma, Waldenstrom macroglobulinemia, monoclonal gammopathy of undetermined significance, and monoclonal Ig deposition diseases, the latter including primary amyloidosis and nonamyloidotic types. These disorders are histologically composed of plasma cells, or plasmacytoid cells which produce Ig that is synthesized and usually secreted and can be deposited in some diseases. The Ig can be complete or can be composed of either heavy or light chains and is termed M-(monoclonal) protein. In MM, this proliferation overwhelms the normal cellular counterparts that synthesize and secrete appropriate levels of Ig. Immunosecretory disorders have been classified in multiple schemes, mostly morphologic, to such a degree that the classification of these entities has become a challenge to pathologists. The World Health Organization classification in 2001 was helpful because it provided specific clinicopathologic criteria for diagnosis. However, terms such as "progressive" disease were not well defined. In 2003, the International Myeloma Group defined MM as a disease with related organ and tissue injury, serving to better explain progressive in terms of deterioration of organ (renal, bone, and bone marrow) function over time. Therefore, modern classification of immunosecretory diseases is based on integration of clinical, morphologic, laboratory, radiographic, and biologic (including molecular) parameters, which we review here.

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.

Ig Heavy Chain Promotes Mature B Cell Survival in the Absence of Light Chain

Survival of mature B cells is thought to depend on the BCR signaling (BCR) because ablation of either H chain (HC) expression or BCR signaling causes B cells to rapidly disappear. Whether a complete BCR is required for survival of mature B cells is not known. To address this question, we generated a mouse in which we can repress the expression of a transgenic Ig L chain (IgL) by doxycycline (IgL-repressible mouse). Repression of IgL abrogated expression. Surprisingly, however, IgL-negative B cells survived longer than 14 wk, expressed signal-competent HC on the cell's surface, and active unfolded protein response factors. Like postgerminal center B cells, IgL-negative B cells were small lymphocytes, not dividing and expressed Bcl-6. Our results indicate that expression of unpaired HC, as it may occur as a consequence of Ag ligation, somatic hypermutation, or receptor editing, facilitates the survival of cells either by inducing receptor signaling or by inducing unfolded protein response and/or the expression of survival genes such as Bcl-6.

Generation of heavy-chain-only antibodies in mice

We have generated transgenic mice containing hybrid llama/human antibody loci that contain two llama variable regions and the human D, J, and Cmu and/or Cgamma constant regions. Such loci rearrange productively and rescue B cell development efficiently without LC rearrangement. Heavy-chain-only antibodies (HCAb) are expressed at high levels, provided that the CH1 domain is deleted from the constant regions. HCAb production does not require an IgM stage for effective pre-B cell signaling. Antigen-specific heavy-chain-only IgM or IgGs are produced upon immunization. The IgG is dimeric, whereas IgM is multimeric. The chimeric HCAb loci are subject to allelic exclusion, but several copies of the transgenic locus can be rearranged and expressed successfully on the same allele in the same cell. Such cells are not subject to negative selection. The mice produce a full antibody repertoire and provide a previously undescribed avenue to produce specific human HCAb in the future.

A 59-Year-Old Woman With Immunotactoid Glomerulopathy, Heavy-Chain Disease, and Non-Hodgkin Lymphoma

Immunotactoid glomerulopathy is one of several renal disorders characterized by the extracellular deposition of nonamyloid fibrillary deposits. There is considerable debate as to whether immunotactoid glomerulopathy should be distinguished from fibrillary glomerulonephritis, a closely related entity. Currently, the distinction is based on fibril size and arrangement. We report the case of a 59-year-old woman in whom a diagnosis of immunotactoid glomerulopathy was made after a 2-year history of proteinuria. Electron microscopy of her renal biopsy showed randomly arranged microtubular subepithelial and mesangial deposits, which measured 34 nm in average diameter. She was later discovered to have circulating immunoglobulin G heavy chains without associated light chains (γ-heavy-chain disease) and, subsequently, non-Hodgkin lymphoma, follicular lymphoma, grade I (World Health Organization classification). Approximately 100 cases of γ-heavy-chain disease have been reported in the literature since it was originally described by Franklin in 1964. However, while there are 10 reports in the literature of heavy-chain disease with fibrillary deposits in the kidney, none fit the criteria for immunotactoid glomerulopathy.

Successful treatment of mu-heavy chain disease with fludarabine monophosphate: a case report

Heavy chain diseases (HCD) are monoclonal lymphoproliferative disorders of B-cells characterized by the synthesis of truncated heavy chains without associated light chains. In patients with mu-HCD, which is a very rare form of HCD, neoplastic cells produce immunoglobulin M heavy chain. The prognosis for patients with mu-HCD is poor, and there is no specific treatment for mu-HCD. In this report, we present a patient with mu-HCD accompanied by splenomegaly and thrombocytopenia. We treated this patient with the fludarabine monophosphate therapy we use for patients with B-cell chronic lymphocytic leukemia. After 5 courses of fludarabine monophosphate treatment, the splenomegaly and thrombocytopenia improved. Fludarabine monophosphate therapy may be a new strategy to improve the prognosis of patients with mu-HCD.

Plasma cell dyscrasias and amyloidosis

The plasma cell dyscrasias and amyloidosis are distinct clinical entities that may co-exist. Both disease processes may present with manifestations in the head and neck, making familiarity with these conditions by otolaryngologists essential. Prompt diagnosis and evaluation for systemic disease are crucial in proper treatment planning.

Gamma-heavy chain disease: review of 23 cases

We report the cases of 23 patients with gamma-heavy chain disease seen at our institution (8 patients previously reported, 15 new patients). There were 15 women and 8 men; the median age at diagnosis was 68 years (range, 42-87 yr). Sixteen patients had an associated lymphoplasma cell proliferative disorder, 3 had a lymphoplasma cell proliferative disorder and an autoimmune disorder, another 3 had an autoimmune disorder only, and 1 had no underlying disease. The lymphoplasma cell proliferative disorder was disseminated in 10 patients and localized in 6. Patients with localized lymphoplasma cell proliferative disorder included 3 with plasmacytoma (1 tongue, 1 submandibular area, and 1 thyroid), 2 with lymphoplasma cell proliferative disorder involving the bone marrow only, and 1 with amyloid of the skin. At the time of diagnosis, lymphadenopathy was present in 8 patients, splenomegaly in 7, and hepatomegaly in 1. A monoclonal spike on serum protein electrophoresis was documented in 19 patients. gamma-Heavy chain was documented by immunofixation in the serum of all patients; 2 had an additional immunoglobulin M-lambda. gamma-Heavy chain was present in the urine in 19 of 22 patients. Sixteen patients were treated for lymphoplasma cell proliferative disorder or autoimmune disorder (14 with chemotherapy, 1 splenectomy, and 1 thyroidectomy followed by radiation therapy). For 5 patients, treatment was not felt to be necessary; 2 patients were thought to be too sick for treatment. Of the 16 patients treated, 6 had a complete clinical response (in 2, gamma-heavy chain disappeared; in 2, gamma-heavy chain persisted; and for 2, no serologic follow-up was available); in 10 patients, clinical disease persisted (in 3, gamma-heavy chain disappeared; in 6, it persisted; and for 1, no serologic follow-up was available). Of 7 patients not treated, 2 died within 5 months; 1 died after 15 months; 2 had no clinical disease at latest follow-up, although gamma-heavy chain persisted; and 2 had no change in clinical and serologic status. The median duration of follow-up was 33 months (range, 1-261 mo). Median survival was 7.4 years.

The transient expression of pre-B cell receptors governs B cell development

Only a subpopulation of relatively large pre-B cells express pre-B cell receptors (preBCR) that can be seen with very sensitive immunofluorescence methods. Inefficient assembly of the multicomponent preBCR coupled with their ligand-induced endocytosis may account for the remarkably low in vivo levels of preBCR expression. Signaling initiated via the preBCR promotes cellular proliferation and RAG-1 and RAG-2 downregulation to interrupt the immunoglobulin V(D)J gene rearrangement process. Silencing of the surrogate light chain genes, VpreB and lambda5, then terminates preBCR expression to permit cell cycle exit, recombinase gene upregulation, and VJ(L) rearrangement by small pre-B cells destined to become B cells.

Heavy chain disease

The heavy chain diseases (HCDs) are rare B-cell malignancies that are distinguished by the production of a monoclonal immunoglobulin heavy chain (HC) without an associated light chain by the malignant B-cells. There are three types of HCD defined by the class of immunoglobulin (Ig) HC produced: IgA (alpha-HCD), IgG (gamma-HCD), and IgM (mu-HCD). Alpha-HCD is the most common and occurs most commonly as intestinal malabsorption in a young adult from a country bordering the Mediterranean Sea. Treatment consists of antibiotics and improved nutrition and hygiene. Surgery is occasionally required for patients with bulky masses at risk for bowel perforation. If there is no response to antibiotics or if aggressive non-Hodgkin's lymphoma (NHL) is diagnosed, the patient should be treated with chemotherapy. Gamma- and mu-HCD are rare and essentially are found in patients with a B-cell NHL that produces an abnormal Ig heavy chain. These patients occasionally may be diagnosed with a monoclonal gammopathy of undetermined significance (MGUS). Patients with MGUS with NHL should be administered chemotherapy. Screening the serum and urine of patients with lymphoplasmacytoid NHL would likely identify more patients with gamma- or mu-HCD.

Gastrointestinal lymphoma: prevention and treatment of early lesions

Gastrointestinal lymphomas comprise a group of distinct clinicopathological entities. Differences in lifestyle and environmental factors between countries could account for the variety in the distribution of the main subtypes: low-grade B-cell lymphomas of the mucosa-associated lymphoid tissue type, alpha-chain disease and enteropathy (coeliac disease)-associated T-cell lymphoma (EATL). The possibility of preventing these lymphomas implies a knowledge of their natural history together with an identification of potential predisposing factors. The development of the lymphoid hyperplasia and subsequently low-grade lymphoma with the possibility of high-grade transformation is a multifactorial process involving both antigenic and host-related factors. The pathogenic role of Helicobacter pylori and gluten has been demonstrated in gastric lymphoma and enteropathy-associated T-cell lymphoma respectively, while environmental factors, especially non-specific bacterial ones, may play a major role in the pathogenesis of alpha-chain disease. The most difficult task in preventing these lymphomas is the recognition of early lesions likely to regress after the removal of the exogenous stimulus.

Expression of a free gamma heavy chain in serum following autologous stem cell transplantation for IgG kappa multiple myeloma

A 41-year-old male with IgG kappa multiple myeloma is described. He developed a free gamma heavy chain without an accompanying light chain following high-dose chemotherapy and autologous peripheral blood stem cell transplantation. The free gamma heavy chain was detected in serum and urine specimens 2 months after transplant, and eventually evolved into an IgG kappa monoclonal protein with electrophoretic properties similar to the original myeloma protein. Although the origin of the free gamma heavy chain remains uncertain, it was most likely related to the underlying plasma cell malignancy and, therefore, was an early sign of disease relapse.