Study on the Mechanism of False Low Measurement of IgG-Binding (Affinity) IgM Type M Protein by Turbidimetric Immunoassay.

BACKGROUND: The purpose of this study was to investigate the immunological and physical characteristics of IgM-λ type M-protein from patients who were measured low in the turbidimetric immunoassay (TIA) IgM assay without error codes for high concentration to determine the cause of the false low levels and to clarify the mechanism of their occurrence. METHODS: Materials were IgM patient samples and 8 serum samples from other IgM M-protein patients as controls. Patient samples were assayed by the TIA method, in which five manufacturers and six models (two reagent manufacturers) share the principle, and the BN ProSpec method (nephelometric method), which has a different principle. Dilution linearity tests, IgG addition experiments, isoelectric point electrophoresis, and hydrophobic chromatography were performed on patients and subjects. In addition, the binding capacity of γ-globulin by BIACORE was also examined. RESULTS: The reaction curve of the patient IgM curved downward when the concentration of IgM exceeded 20 g/L, and no error code was obtained. In the measurement by the TIA method of five manufacturers and six models, patient IgM was measured at a false low level with no error code obtained in undiluted dilution by any of the instruments and reagents, but could be measured without any problem by the nephelometric method. In addition, in the patient IgG addition experiment, only patient IgM showed a false low level under high IgG concentration. Furthermore, the binding capacity of patient IgM to γ-globulin (IgG) by BIACORE was significantly higher than that of the control IgM-type M protein. CONCLUSIONS: Patient IgM has an affinity (binding capacity) for IgG and forms an IgM-IgG complex under conditions of high IgG concentration. It was speculated that this complex inhibited the reaction with the anti-IgM antibody and the absorbance of the second reaction did not increase, suggesting a false low.

Glycosylated Bence Jones Protein with Poor Thermal Reactivity in Heat Coagulation Tests.

BACKGROUND: We experienced a patient with multiple myeloma whose urine contained a considerable amount of Bence Jones protein (BJP), which demonstrated poor thermal reactivity in heat coagulation test. The mechanism for this phenomenon was assessed. METHODS: Immunoelectrophoretic analyses reveal that a band corresponding to BJP in the urine had 2,600 Dalton by reduction after glycosidase treatment, but not after sialidase treatment. In addition, the glycosidase-treated urine tested positive in heat coagulation test. CONCLUSIONS: Glycosylation of the immunoglobulin light chain, which has rarely been seen, is the cause of the unexpected behavior of this patent's BJP in heat coagulation tests.

A Case of Waldenstrom Macroglobulinemia with Temporary Appearance of 7S IgM Half Molecule.

BACKGROUND: We encountered a rare case of Waldenstrom macroglobulinemia with temporary appearance of 7S IgM half molecule and with monoclonal proteins binding to agarose gel. METHODS: The patient's serum and urine were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The N-terminal amino acid sequences of the IgM with abnormal mass (68 kDa) were determined and compared with those of known immunoglobulin. RESULTS: The 68 kDa IgM consisted of a defective µ chain (36 kDa) and an intact κ chain. N-terminal amino acid sequence analysis demonstrated that the defective µ chain had the variable region of IgM. The agarose gel-binding ability of the IgM-κ M-protein was lost after reduction or alkaline treatment of serum. CONCLUSIONS: The 7S half molecule IgM in the present case may miss a large part of the constant region of the µ chain.

[Divergence between measured values of total IgG and subclass IgGs (sum of IgG1-IgG4) in IgG4-related disease].

In systemic IgG4-related disease, an elevation of the serum IgG4 level(IgG4: 135 mg/dl or higher) and IgG4-positive plasma cell infiltration occurs. Since the total IgG and sum of subclasses, IgG1 through IgG4, were markedly different in a patient suspected of having Mikuliez's disease, we investigated the relationship between total IgG and sum of IgG subclasses. The subjects were healthy individuals, and low IgG4, high IgG4, hyper-gamma globulinemia and hypo-y globulinemia groups. Total IgG was measured using 'N-assay TIA IgG-SH' (Nittobo) and Hitachi 7700, and IgG subclasses were measured using BS-NIA reagent (Binding Site) and BN II (Siemens). Designation of total IgG and the sum of IgG subclasses was established in the healthy control subjects. However the total IgG level and sum of IgG1-4 levels were different when the balance among the IgG subclasses was lost. In case such as :1) the IgG4 level was high and 2) IgG1-type M protein was present. These results indicate that the reevaluation of measured data is necessary when the IgG4 concentration is high and the difference between total IgG concentration and the sum of IgG subclasses is large.

[Efforts of medical technologists for cancer patients--a questionnaire survey following a lecture meeting: "cancer treatment and clinical examinations" for cancer patients and their families].

As interprofessional work in cancer treatment becomes increasingly important, medical technologists are required to play active roles as part of the team. The cancer center of our hospital organized a lecture meeting, "The 6th Lecture Meeting: Living Together," for cancer patients and their families, and a medical technologist presented a lecture entitled: "Cancer treatment and clinical examinations." According to the results of a questionnaire survey conducted following the meeting, most participants were able to understand the lecture and were satisfied with it. Based on the opinions expressed by meeting participants and the questionnaire results, medical technologists initiate the following services and activities: 1. They explain the results of white blood cell and neutrophil counts of patients on chemotherapy and/or radiation therapy; and 2. provide medical examinations and consultation at outpatient chemotherapy centers. We believe that these efforts will help improve cancer treatment and further contribute to interprofessional health care.

A new type of temperature-dependent serum M protein: a case of IgG-lambda type multiple myeloma.

BACKGROUND: We report a rare case of temperature-dependent serum M protein (thermoprotein), monoclonal IgG(1)-lambda protein isolated from 90-year-old female with advanced multiple myeloma. METHODS: M protein was identified in the blood plasma of the patient by immunoelectrophoresis (IEP). To evaluate the types of bonds, the properties of the protein after reduction and chemical treatment were examined. RESULTS: This protein was irreversibly precipitated at or above room temperature when exposed in the air. This protein was redissolved by 30 mmol/l dithiothreitol, 4 mol/l urea, or 8 mmol/l EDTA. CONCLUSIONS: Unlike other immunoglobulins reported to date, this data suggests that hydrogen, disulfide, and ionic bonds are involved in the temperature-dependent precipitation of this M protein.