IgM pyroglobulinemia with erythrocytosis presenting as hyperviscosity syndrome. II. Biochemical properties and mechanisms of pyrogel formation.

An immunoglobulin M with kappa light chains (IgMK) pyroglobulin from a patient with hyperviscosity syndrome, erythrocytosis and coagulation defects has been studied for its immunochemical properties. At physiologic temperatures the purified macropyroglobulin showed a striking tendency to aggregate in the pentamer as well as in the monomer form. This property was also observed in its H chains. Aggregate formation of the pentamers may have contributed to the blood viscosity and coagulation defects. Formation of pyrogel at 56degreesC was observed with pentamers as well as monomers, but not with separated H or L chains. Amino acid analysis showed quantitative abnormalities of aspartic acid, glycine, cystine and leucine within the H chains. Solubility of the pyrogel in sodium dodecyl sulfate, the pyroglobulin's tendency to aggregate and the cystine deficit of H chains implicate conformational changes leading to hydrophobic bonding at 56degreesC in the formation of pyrogel.

IgM pyroglobulinemia with erythrocytosis presenting as hyperviscosity syndrome. I. Clinical features and viscometric studies.

The hyperviscosity syndrome is described in a patient with erythrocytosis and an immunoglobulin M with kappa light chain (IgMK) macroglobulinemia. Viscometric studies were carried out on whole blood and demonstrated the contribution of both the increased hematocrit value and the macroglobulinemia to the whole blood viscosity. Clinical improvement followed phlebotomy and was accompanied by a decrease in whole blood viscosity. Continued treatment with chlorambucil has been associated with a long symptom-free period. The macroglobulin was characterized as a monoclonal IgMK pyroglobulin which retained its thermoprecipitability was reduced to 7S monomers. The presence of IgMK aggregates in the serum may have contributed to the increase in blood viscosity.

3. The laboratory investigation of monoclonal gammopathies.

The monoclonal gammopathies are a group of disorders characterized by proliferation of a single clone of plasma cells that produce a homogeneous, monoclonal (M) protein. The structure of immunoglobulins, relationship of normal (polyclonal) immunoglobulins to myeloma and macroglobulin (monoclonal) immunoglobulins, pattern of monoclonal immunoglobulin overproduction, and laboratory methods for the recognition and study of monoclonal proteins in the serum and urine are reviewed. Interpretation of these laboratory tests is emphasized. The demonstration of a monoclonal protein in the serum or urine of a patient suggests multiple myeloma or one of its variants (solitary plasmacytoma of bone, extramedullary plasmacytoma, or plasma cell leukemia); Waldenström's macroglobulinemia or, occasionally, lymphoma; heavy-chain diseases (gamma, alpha, and mu); primary amyloidosis; and monoclonal gammopathies of undertermined significance. The electrophoretic and immunoelectrophoretic patterns found in the monoclonal gammopathies are discussed. Periodic electrophoresis of the serum and urine is essential in the follow-up and management of patients with a monoclonal gammopathy.

IgE pyroglobulinemia in multiple myeloma.

A new case of IgE/K myeloma in a 38-year-old male is described. The clinical course, bone marrow picture and serum electrophoretic pattern were typical of multiple myeloma. Heating of the serum at 56 degrees C induced an irreversible gel formation or pyroglobulin that was isolated and proved to be identical to the IgE paraprotein, by biochemical and immunochemical methods. The thermoprecipitability was abolished by treatment with urea, sodium dodecyl sulphate and neutral salts and not inhibited by sugars, alcohols, 2-beta-mercaptoethanol and guanidine HCl. The association of an IgE myeloma protein with a pyroglobulin is a finding not previously reported in a myeloma of this class.

IgD plasma cell leukemia associated with pyroglobulinemia and pyroglobulinuria.

A 70-yr-old man with multiple myeloma IgD developed a plasma cell leukemia producing a serum IgD monoclonal peak and lambda light chains in the urine. When the serum and the urine were heated at 56 degrees C for 30 min both monoclonal bands disappeared. The precipitate failed to redissolve on heating to 100 degrees C. Ion exchange chromatography with a linear gradient of phosphate buffer, pH 8, 0.020-0.300 mol/l and column electrofocusing showed that the serum pyroglobulin was eluted with buffer concentration between 0.040-0.125 mol/l and had an isoelectric point of 5.02, while the pyroglobulin of the urine was eluted with 0.020-0.033 mol/l and had a pI = 7.16. The serum and urine pyroglobulins had a total antigenic community with their correspondent purified proteins. The isolated lambda chains did not change when they were heated at 56 degrees C for 30 min, nevertheless, the heated purified IgD shows some changes in its isoelectric point, molecular mass and antigenicity. These changes in the purified IgD suggest that the pyroprecipitability could be due to conformational features.

The physicochemical properties and the process of pyrogel formation of IgD pyroglobulin.

The extremely rare IgD pyroglobulin caused opalescence, lost its antigenicity and acquired more negative charge when heated for 30 min at 56 degrees C. Exposure to 60 degrees C for 60 min produced a firm gel. The thermoprecipitability was abolished by the treatment with guanidine, urea and sodium dodecyl sulfate, but not by 2-mercaptoethanol or neuraminidase, and required the presence of both heavy and light chains. However, amino acid analysis showed abnormalities only in the heavy chain. We hypothesize that the irreversible heat-induced aggregation of IgD pyroglobulin is the result of a conformational change, triggered by light chain, which increases the molecular hydrophobicity.

Immunochemical characterization of monoclonal protein in the serum of a patient with Waldenstr]om's macroglobulinemia showing both pyroglobulin and cryoglobulin properties.

A patient with Waldenstr]om's macroglobulinemia whose serum demonstrated properties of both pyroglobulin and cryoglobulin was studied. A monoclonal (M) protein in the serum of the patient was identified by immunoelectrophoresis (IEP) and immunofixation electrophoresis (IFE) as IgM-lambda. The M-protein was separated by gel permeation high-performance liquid chromatography (HPLC). Cryoglobulin in the serum was isolated by the method of cold precipitation. The cryoglobulin was identified as IgM-lambda type by IEP and was the same M-protein as that which occurred in this patient's serum. The purified cryoglobulin also had the properties of a pyroglobulin. Neither property disappeared following pretreatment with 2-mercaptoethanol (2-ME), urea, and Triton X-100 detergent, and deglycosylation with N-glycanase (E.C. 3.5.1.52). We suggest that these abnormal properties were caused by the molecular abnormality of the IgM-lambda M-protein.

Monoclonal cryoglobulins and pyroglobulins.

In a series of 1182 monoclonal Ig, the authors demonstrated 10 cases with monoclonal cryoglobulin (0.8%) and 5 cases with pyroglobulin (0.42%) in the serum; in two of these cases both thermoproteins were present simultaneously. One observation revealed mixed cryoglobulin consisting of monoclonal IgM-kappa and polyclonal IgG. In 70 Waldenström's macroglobulinemias, monoclonal cryoglobulin occurred in 10%, pyroglobulin in 5.71%. In a subgroup of 744 monoclonal IgG, monoclonal cryoglobulin was demonstrated in 3 cases (0.4%), pyroglobulin in one case (0.13%).