Search

Monoclonal gammopathies are characterised by the production of a monoclonal immunoglobulin or free light chains by an abnormal plasma cell or B-cell clone and may indicate malignancy or a precursor (MGUS). There is currently no consensus on the initial test or combination of tests to be performed in suspected monoclonal gammopathies but serum protein electrophoresis and urine protein electrophoresis are commonly requested as initial investigations. If abnormal, immunofixation electrophoresis is then performed to confirm the presence of paraprotein and to determine its heavy and light chain type. Recently, some groups have developed simplified "screening" IFE methods for use in parallel to SPEP for the detection monoclonal gammopathies. We argue here that screening IFE may be of benefit in clinical laboratories using SPEP with poor resolution in the β-region, assisting in the detection of mainly IgA paraprotein, but may be of less benefit in laboratories utilising higher resolution gels. Further it may increase the detection of trace bands of questionable clinical significance, representing transient phenomena in infectious and auto-immune conditions or very low risk MGUS. The increased detection of these bands using screening IFE would require further patient follow up, possibly causing unnecessary patient anxiety and additional follow up healthcare costs.

The reliable detection of paraprotein in serum and urine is the primary purpose of electrophoretic procedures in clinical laboratories. Screening immunofixation electrophoresis (sIFE) employs a single application of antisera directed against heavy and light chains that facilitates the detection of paraproteins that migrate in the non-γ region or that are below the detection limit of protein electrophoresis. These paraproteins that are missed by routine electrophoresis occur in up to 27.3% of newly investigated and 13.6% of monitored patients. Small paraproteins missed by conventional electrophoretic techniques are clinically important in the diagnosis and monitoring of malignant plasma and B-cell disorders. The superior diagnostic performance of sIFE makes it suitable as the initial laboratory procedure to investigate paraproteins in complex serum and urine matrices.

Articles have debated whether or not urine analysis remains valuable for identifying monoclonal gammopathies. A general impression is that the newer serum free light chain (FLC) assay is more analytically sensitive, more quantitative and simpler to perform. Many laboratory directors may have seized on the idea of eliminating urine analysis because it is a tedious procedure and requires expert interpretation while most laboratories can perform automated serum FLC assay. Others have concluded that urine immunofixation electrophoresis (IFE) optimizes the diagnostic sensitivity and should be included when there is a clinical indication. Here, I show that papers faulting urine analysis often used inappropriate urine methodology and this helps explain why there was misinterpretation. Moreover, the literature, shows urine IFE is often more sensitive for identifying low-level monoclonal FLC than the serum assay because urine IFE is as sensitive when performed appropriately and generally more specific. Besides, the reference range for serum FLC assay is unclear which is a great problem in assessing response to treatment and in identifying diseases when there is low concentration monoclonal FLC. I conclude that urine IFE remains important and is complementary to serum FLC assay, although the best algorithms for use remains to be elucidated.

By crossed-immunoelectrophoresis (CIE) of plasma, using anti-inter-alpha-trypsin inhibitor (ITI) immunoglobulins, beside native ITI, related components are visualized as an heterogeneous peak migrating farther than ITI. The area corresponding to this peak is largely increased in case of inflammatory disease. So, quantitative CIE has been previously proposed for discrete evaluation of ITI and its derivatives. We herein present evidence that CIE does not allow a clear separation of ITI from its derivatives: in this system, they are to some extent coprecipitated. Therefore the resulting overestimation of ITI may explain the previously reported absence of inverse relation between relative contents of ITI and derivatives in case of inflammatory disorders. Our data confirm the view that ITI acts as a precursor of smaller immunologically related inhibitors.

After a brief review of the known techniques for the identification of crossed immunoelectrophoresis peaks, the authors claim that the technique of Platt et al (1973), Clin. Chim. Acta 46, 419-429) is the most effective. This consists of blocking a protein in the first run, thereby causing the disappearance of the corresponding peak in the second dimension. The advantages of this technique with respect to the others are discussed.

Quantitative determination of proteins has been made by electrophoresis thereof in tubular canals filled with agarose gel containing antibodies. The procedure is simple and practicable. Sample volumes of a few microliter up to some hundred microliter may be added for each test. The amount of protein in a sample was found to be linearly related to the distance from the point of application (i.e. gel surface) to the front of the immunoprecipitation zone. The zone immunoelectrophoresis method shows over rocket immunoelectrophoresis the following advantages: less consumption of antibodies; much lower detection limit (0.05 microgram of protein per ml); larger concentration range with a linear calibration curve. A high correlation (0.98) between the first- and last-mentioned method was obtained for alpha 1-antitrypsin. Precision data are given for albumin and alpha-fetoprotein and typically a relative standard deviation of a few percent was obtained.

Plasminogen-binding human alpha 2-plasmin inhibitor is converted by human granulocyte elastase into its non-plasminogen-binding and finally into the inactive form of the inhibitor. This degradation of the plasmin inhibitor, described earlier as "spontaneously" occurring conversion, is shown in dodecyl sulfate polyacrylamide gel electrophoresis, in two-dimensional immunoelectrophoresis and by measuring the kinetics of plasmin inhibition. Experiments in the presence of normal human plasma required unphysiologically high concentrations of elastase to inactivate alpha 2-plasmin inhibitor, suggesting a role of elastase in this type of indirect fibrinolysis in a microenvironment only and not in systemic events.

Human urinary and human pancreatic kallikreins were compared by radioimmunoassay, immunoelectrophoresis, by their enzymatic activity using the substrate Ac-Phe-Arg-OEt and by their biological activity employing the dog blood pressure assay. The only significant difference observed was a higher anodal mobility of the urinary kallikrein under the conditions of immunoelectrophoresis.

The hemocyanins of the scorpions Leiurus quinquestriatus and Androctonus australis, the tarantula Eurypelma californicum (all 24-mers), and the lycosid spider Cupiennius salei (dodecamer) were dissociated into subunits, the subunits isolated and studied by two-dimensional immunoelectrophoresis for interspecific cross-reactivities. Androctonus hemocyanin yielded a pattern of 8 subunit types in agreement with data from Lamy et al. (1979, Arch. Biochem. Biophys. 193, 140-149). Leiurus hemocyanin is also composed of 8 immunologically distinct subunits which could be assigned to the pattern of Androctonus in a subunit-to-subunit correlation. The subunit designations 1 to 6 of Lamy et al. could be adopted for both scorpion hemocyanins; however, in the present communication, Lamy's subunits 3A/3B are designated as 3'/3", because we could not unequivocally decide if 3' = 3A and 3" = 3B or vice versa. The 7 subunit types a to g of Eurypelma hemocyanin could be correlated with the scorpion hemocyanin subunits as follows: a = 3', b = 5B, c = 3C, d = 5A, e = 6, f = 2, g = 4. Additional cross-reactivities were detected between e/4, and f/5A, respectively. No subunit of Eurypelma hemocyanin is homologous to scorpion 3", which could not be precipitated by anti-Eurypelma antiserum. Antiserum against Cupiennius hemocyanin precipitated subunit f of Eurypelma and subunits 2 and 5A of scorpion hemocyanin. The published models of quaternary structure and a possible subunit phylogeny of arachnidan hemocyanins are discussed in view of the present results.