Detection Of Bence-Jones Protein Research Articles

Detection of Bence-Jones protein in practice.

The monoclonal gammopathies are characterized by the presence in serum and/or urine of a monoclonal, intact immunoglobulin or fragment, a so-called monoclonal component, produced by a B-cell clone that has undergone a genetic transformation. The clinical conditions accompanying monoclonal components encompass a wide spectrum, ranging from an entirely asymptomatic non-progressive state, usually detected incidentally, through to a malignant, aggressive multiple myeloma or lymphoma (see Table 1). The particular presentation of a monoclonal gammopathydepends on the exact transformation of the cell and the nature of the monoclonal component produced which may itself exhibit deleterious biological properties (see Table 1). An important part of the investigation of patients with suspected monoclonal gammopathy or a proven serum monoclonal component is the detection of urinary Bence-Jones protein (BJP), a monoclonal immunoglobulin light chain. This is for a variety of reasons. Firstly, the detection of a monoclonal component is central to the diagnosis of myeloma, and between 14% and 20% of cases of myeloma are characterized by BJP as the only monoclonal component. Secondly, it was observed in early studies that the presence of BJP was highly predictive of a malignant monoclonal gammopathy. Despite the occasional reports of cases classi®ed as monoclonal gammopathy of undetermined signi®cance excreting BJP of up to 1 g/24 h, the presence of BJP is today regarded as central to the initial assessment of the patient presenting with a serum monoclonal component. It is also important in assessing prognosis and directing subsequent management of a patient with a serum monoclonal component in whom the initial diagnosis is uncertain. Thirdly, in those conditions arising from deposition of aggregates of monoclonal light chains ± AL amyloidosis and light chain deposition disease ± detection of urinary BJP may provide an important pointer to the presence of the disease and subsequent investigation and, for AL amyloidosis, early treatment. The importance of the detection of urinary BJP is thus not in doubt. However, a recent survey by the UK National External Quality Assessment Scheme (NEQAS) for monoclonal protein revealed uncertainty as to the desired detection limit for BJP and, partly as a consequence of this, a subsequent distribution indicated that 35% of laboratories were unable to detect BJP at approximately 60mg/L. There Personal View Ann Clin Biochem 2000; 37: 563±570

Detection of Bence-Jones protein in serum by immunoblotting.

To detect Bence-Jones protein (BJP) in serum we precipitated intact immunoglobulins (Ig) using polyethylene glycol (PEG) and subjected the BJP in solution to electrophoresis in agarose gel, followed by transfer to a polyvinylidene difluoride membrane, and immunoenzymatic staining (successively using rabbit anti-human light/heavy chain of Ig, biotinylated swine anti-rabbit Ig, and alkaline phosphatase-conjugated streptavidin). Treatment with PEG effectively reduced background staining of polyclonal Ig in the immunoblots, although intact monoclonal Ig was not always completely removed. To compare the present method with immunoelectrophoresis (IEP), we selected samples from patients demonstrating BJP by IEP in both serum and urine (n = 40), serum only (n = 18), and urine only (n = 32); 21 of these patients had BJP alone and 69 had BJP in addition to intact monoclonal Ig. Efficiency of detection of BJP in serum was increased by the present method: serum BJP was detected in 70 patients by the present method versus 58 by IEP. The present method demonstrated single BJP bands in the samples from 16 patients (kappa, n = 7; lambda, n = 9) and multiple BJP bands (range: 2-9) in the samples from 54 patients (kappa, n = 31; lambda, n = 23). This method could be useful for detecting BJP in serum from patients suspected of having light chain gammopathy (without the need for urine testing) and may complement urine testing in patients excreting polyclonal free light chains of Ig.

Detection of Bence-Jones protein by isoelectricfocussing of unconcentrated urine followed by nitrocellulose blotting and immunoperoxidase staining

Urine specimens from 164 patients sent to the laboratory for testing for Bence-Jones proteinuria were investigated using a new procedure. The protein in the untreated urine was subjected to isoelectricfocussing in an agarose gel, transferred to a nitrocellulose membrane by blotting, and then stained by an immunoperoxidase technique for either immunoglobulin kappa or lambda chains. This technique was compared with a routine procedure for the detection of immunoglobulin light chains involving concentration by ultrafiltration, electrophoresis and then immunofixation. The new technique achieved a much increased rate of detection of Bence-Jones proteinuria. Among 51 patients known to have myeloma or macroglobulinaemia, Bence-Jones proteinuria was detected in 35 cases with the new procedure and in only 27 by the conventional method. In 28 patients with paraproteinaemia without other evidence of myeloma, macroglobulinaemia, leukaemia or lymphoma, 12 instances of Bence-Jones proteinuria were discovered with the new procedure, 10 of which were missed by the conventional method. The improved efficiency of detection is attributed to the high resolution of isoelectricfocussing and the avoidance of protein loss from adsorption on to ultrafiltration membranes.

Detection of Bence-Jones protein in urine.

Detection of Bence-Jones protein in urine.

A red herring in the detection of Bence-Jones protein.

A red herring in the detection of Bence-Jones protein.