IgM paraproteins

Characteristics and Prognosis of Patients with Immunoglobulin M Monoclonal Gammopathy

Many patients with immunoglobulin M (IgM) monoclonal gammopathy remain asymptomatic and, consequently, untreated; however, few studies have evaluated the clinical course and prognosis of these patients. Using the screening procedures at our hospital, 74 patients with IgM monoclonal gammopathy were selected. We excluded 11 patients in whom the treatment for lymphoid neoplasms had been initiated at the time of IgM monoclonal protein detection. The remaining 63 patients were considered to be the patient population with IgM MGUS and asymptomatic WM, and were analyzed. In these patients, the median overall survival was longer than 14 years. More than half of these patients died from causes other than lymphoid neoplasm. The cumulative incidence of lymphoid neoplasm requiring treatment was 17.5%. In five of eight patients requiring treatment for lymphoid neoplasms, the causes of death were related with these lymphoid neoplasms. Our study suggests that not all patients with IgM monoclonal gammopathy require uniform treatment for prolonged survival; however, most lymphoid neoplasms requiring treatment are refractory diseases. Our findings may help manage patients with macroglobulinemia.

Immunoglobulin m monoclonal gammopathy of undetermined significance and smoldering Waldenström macroglobulinemia

Monoclonal gammopathy of undetermined significance of the immunoglobulin M class was diagnosed in 213 patients at the Mayo Clinic, 29 (14%) of whom developed lymphoma, Waldenström macroglobulinemia, or a related disorder over 1567 person-years of follow-up. The cumulative probability of progression was 10% at 5 years, 18% at 10 years, and 24% at 15 years, or approximately 1.5% per year. The concentration of serum monoclonal protein at diagnosis and the initial serum albumin value were the only independent predictors of progression with multivariate analysis. By contrast, during 285 person-years of follow-up, 34 (71%) of 48 patients with smoldering Waldenström macroglobulinemia (SWM) progressed to Waldenström macroglobulinemia (WM), which required therapy, along with amyloid light chain (AL) amyloidosis (1) and lymphoma (1). The cumulative probability of progression was 6% at 1 year, 39% at 3 years, 59% at 5 years, and 65% at 10 years. The percentage of lymphoplasmacytic cells in the bone marrow, size of the serum monoclonal (M) spike, and hemoglobin value were significant independent risk factors for progression.

Prognostic factors and predictors of outcome of immunoglobulin M monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) of the immunoglobulin M (IgM) class was diagnosed at our institution in 213 patients who resided in the 11 counties of southeastern Minnesota from 1960 to 1994. The median age at diagnosis was 74 years and the median concentration of serum M-protein was 1.2 g/dL. The 213 patients were monitored for 1567 person-years (median, 6.3 years), during which 71% died. During follow-up, non-Hodgkin's lymphoma (n = 17), Waldenstrom's macroglobulinemia (n = 6), primary amyloidosis (n = 3), and chronic lymphocytic leukemia (n = 3) developed in 29 patients (14%). The number of patients with progression to lymphoid neoplasms was 15.9 times that expected in the general population. The cumulative probabilities of progression to one of these disorders were 10% at 5 years, 18% at 10 years, and 24% at 15 years. The overall average risks for progression were approximately 1.5% per year. Rates of death resulting from other diseases (cardiovascular, cerebrovascular, etc.) were 31% at 5 years, 52% at 10 years, and 65% at 15 years. Multivariate analysis revealed that only the concentration of serum M-protein at diagnosis and the serum albumin value were independent predictors of progression. It was concluded that the patients with IgM MGUS should be followed indefinitely.

Long-term follow-up of IgM monoclonal gammopathy of undetermined significance

Little effort has been made to quantitate adverse outcomes of monoclonal gammopathy of undetermined significance (MGUS) of the immunoglobulin M (IgM) class, which progresses to lymphoma or Waldenström macroglobulinemia, whereas IgA and IgG MGUS progress to multiple myeloma, primary amyloidosis (AL), or a related plasma cell disorder. From 1960 to 1994, IgM MGUS was diagnosed in 213 patients in southeastern Minnesota. The end point was progression to lymphoma or a related disorder, as assessed with the Kaplan-Meier method. The 213 patients were followed up for 1567 person-years (median, 6.3 years per patient). Lymphoma developed in 17 patients (relative risk [RR], 14.8), Waldenström macroglobulinemia in 6 (RR, 262), primary amyloidosis in 3 (RR, 16.3), and chronic lymphocytic leukemia in 3 (RR, 5.7). The relative risk of progression was 16-fold higher in the patients with IgM MGUS than in the white population of the Iowa Surveillance, Epidemiology, and End Results Program. Cumulative incidence of progression was 10% at 5 years, 18% at 10 years, and 24% at 15 years. On multivariate analysis, the serum monoclonal protein and serum albumin concentrations at diagnosis were the only risk factors for progression to lymphoma or a related disorder. Risk for progression to lymphoma or a related disorder at 10 years after the diagnosis of MGUS was 14% with an initial monoclonal protein concentration of 0.5 g/dL or less, 26% with 1.5 g/dL, 34% for 2.0 g/dL, and 41% for more than 2.5 g/dL.

IgM paraproteinaemia: disease associations and laboratory features

AIMS

To review the disease associations and laboratory features occurring in IgM paraproteinaemia.

METHODS

Systematic review of all new serum IgM paraproteins detected over a 6-year period in an immunodiagnostic laboratory serving a population of 400,000 people. Clinical diagnoses were ascertained from a computerised laboratory database or clinical notes, whilst associated laboratory features were obtained from the same sources.

RESULTS

The 125 IgM paraproteins detected constitute 19.7% of all new paraproteins observed over the period of study. IgM paraproteinaemia occurred more commonly in males and its frequency increased with age. Approximately 30% were associated with B cell lymphoproliferative disorders (Waldenstrom's macroglobulinaemia, non-Hodgkin's lymphoma, chronic lymphocytic leukaemia, amyloid, etc.) with the remainder being labelled as monoclonal IgM gammopathies of uncertain significance (four having a peripheral neuropathy). At clinical presentation, patients with lymphoproliferative disorders tended to have higher levels of IgM, beta2-microglobulin, the presence of free urinary light chains and demonstrated molecular size heterogenicity of the paraprotein (presence of decamers, oligomers and monomers in addition to the pentamer) but there was considerable overlap. A good correlation was noted between paraprotein concentration and viscosity in most patients.

CONCLUSION

IgM paraproteinaemia was most frequently encountered in the context of a gammopathy of uncertain significance. Features which suggested lymphoproliferative disorders included higher levels of paraprotein (>15 g/l) elevated levels of beta2-microglobulin and the presence of urinary free high chain. However, as much overlap was seen, regular monitoring of paraprotein levels is considered mandatory in the management of these patients.

Laboratory investigation of paraproteinaemia

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Polyneuropathy and IgM monoclonal gammopathy: studies on the pathogenetic role of anti-myelin-associated glycoprotein antibody

Attention has recently been directed toward patients having a polyneuropathy and a monoclonal IgM anti-myelin-associated glycoprotein (anti-MAG) antibody. The possibility of a pathogenetic role for the anti-MAG antibody in the evolution of the polyneuropathy and in the development of central nervous system signs, including tremor and ataxia, remains unresolved. In 5 patients with this syndrome whose clinical courses were followed closely, in 1 of whom a complete postmortem examination of the nervous system was performed, we made the following observations: the anti-MAG antibody did not localize to the compact layer of the myelin sheath in affected nerves, but did localize to areas of myelin splitting; anti-MAG antibody present in the sural nerve of an affected individual for 7 years was not associated with progressive pathology; anti-MAG antibody was not deposited in the central nervous system of an affected individual, although the antibody did bind to these same tissues in vitro; deposition of anti-MAG antibody observed at postmortem examination did not correlate with the degree of pathological change; and study of the peripheral nervous system favored a primary axonal neuropathy with secondary demyelination.

B-lymphoproliferative disorders: a proposed unified pathogenetic pathway

The clinical features of lymphoproliferative diseases associated with paraproteinemia are briefly reviewed and correlated with current immunologic concepts in an effort to clarify the pathophysiology of B-lymphocyte disorders. B-lymphocyte maturation proceeds in a predictable manner from the Pre-B cell to the formation of idiotype specific plasma cells and memory B-lymphocytes. The immunoglobulin isotype produced by the mature plasma cell is determined by a site specific process of gene switching which proceeds from mu to alpha production. Lymphoproliferative diseases are the result of disordered B cell maturation and their clinical features can be explained by identifying the locus of the maturational defect.

Autoantibody to nerve tissue in a patient with a peripheral neuropathy and an IgG paraprotein

The antibody activity of a benign IgG lambda paraprotein to nerve tissue in a case of peripheral neuropathy has been investigated using immunohistochemical methods on tyrpsin-treated, formalin-fixed, paraffin-embedded tissue. IgG lambda was found in th sural nerve biopsy of the patient. Specific binding of the purified IgG lambda paraprotein and its isolated F(ab')2 fragment to homologous nerve and brain tissue was demonstrated. Similar activity was not demonstrable on fresh frozen cryostat sections. The results suggest that tests for autoantibodies to nerve tissue in neuropathological disorders should not be confined to fresh frozen tissue substrates.

Significance of immunoglobulin deposition in peripheral nerve in neuropathies associated with paraproteinaemia

Direct and indirect immunofluorescent studies of sural nerves were carried out in two patients with paraproteinaemia and neuropathy, in four other patients with axonal or demyelinating neuropathies, and in one normal sural nerve. IgM was demonstrated directly in the two cases of paraproteinaemia and neuropathy, and indirectly, using the serum of one of these cases, in a case of axonal neuropathy and in one case of chronic Guillain-Barré syndrome. In the latter case, IgM deposition also occurred after exposure to normal serum. These results suggest that the paraprotein itself did not directly cause neuropathy, but that immunoglobulin deposition is probably a secondary process, caused by diffusion into damaged nerves.

Peripheral neuropathy and benign IgG paraproteinaemia

Three patients with peripheral neuropathy and an associated benign IgG paraproteinaemia are described. No direct immunological evidence for an aetiological role of the paraprotein was found, and the implications of this are discussed.

Lymphoproliferative disease with IgM lambda monoclonal protein and autoimmune hemolytic anemia. A report of four cases and a review of the literature

Four patients with lymphoproliferative disease with immunoglobulin M lambda (IgMlambda) monoclonal proteins and severe autoimmune hemolytic anemia are described. These patients had many features in common that may warrant their recognition as a specific entity within the lymphoproliferative spectrum. In each case, a wide thermal range low titer cold agglutinin was present. The association of cold autoimmune hemolytic anemia with IgMlambda monoclonal protein and lymphoproliferative disease is unusual. The literature on IgM monoclonal proteins associated with lymphoproliferative disease is reviewed with emphasis on the presence of direct antiglobulin test positive autoimmune hemolytic anemia.

IgG myeloma presenting as ulcerative colitis

Two patients who presented with ulcerative colitis are described. Both were found to have evidence of IgG monoclonal gammopathy and Bence-Jones proteinuria. This association has been reported previously only in the presence of myelomatous infiltration of the gastrointestinal tract or in amyloidosis, and hence the cases reported appear to be unique.