Monoclonal bands

It cannot be overemphasized that the absence of a monoclonal band of protein in the serum of a patient suspected of having multiple myelomatosis does not rule out the diagnosis. Quite frequently, the suspected patient may be excreting all the paraprotein in the form of a Bence Jones protein into the urine, and hence the simultaneous examination of both the serum and the urine by electrophoresis usually jirovides a rapid and excellent means of diagnosis. 

Fig. 14. Malignant paraproteinemia. Electrophoresis on cellulose acetate of serum (above) and concentrated urine (below) reveals (i) Bence Jones proteinuria. In this case monoclonal bands are seen of each type. For L the relevant concentration to albumin indicates which are IgGL, L dimer, and L monomer (ii) loss of normal y-globulin (iii) a high serum level of paraprotein. Immunoelectrophoresis of urine reveals paraprotein bows of k, and X, yaXj and X2.

A monoclonal band can be found in most cases, but serum must be separated at 37°C. The ESR in the cold is much higher than at 37°C, due to massive agglutination in the cold. The monoclonal IgM is readily measured (C14), averaging 0.4 g/100 ml (range 0.1-2.4). The residual IgM and IgA and IgG are usually normal. In some 30% patients, mostly those with high IgM levels, a subnormal level of IgA is found. The cold agglutinin IgM is mostly well produced, with no Bence Jones proteinuria or 7 S IgM, and, on a molecular basis, specific lytic activity against enzyme-treated red cells was very similar. 

Method The method used is DNA extraction from blood, bone marrow, fresh or formalin-fixed paraffin-embedded tissues, followed by PCR or multiplex PCR. To provide a better discrimination of the monoclonal bands it is advisable to run out the PCR product on a polyacrylamide gel electrophoresis. Heteroduplex assay for the analysis of the PCR product improves the results and minimizes the possibility of false-positive or false-negative results due to improper primer annealing. 

In case of monoclonal cell population, the first two reactions generate a band 130-150bp in size the third reaction generates a monoclonal band 250-300bp in size. 

J Y J12 consensus primer to J1 and J 2 regions JyJp2 consensus primer to J p 1 and Jp 2. PGR carried out in two reactions, first reaction using both V forward primers (primer 1 and 2) with one J reverse primer (primer 3). This reaction generates a band on electrophoreses 75-95 bp in size, second reaction using the same V forward primers with the other J reverse primer (primer 4). This reaction generates a monoclonal band (or two bands) on electrophoreses 80-110 bp in size. 

A monoclonal electrophoresis with monoclonal bands is generated if a monoclonal cell population is present. 

Figure 2 Serum electrophoresis of a patient with a small monoclonal band (top) CE (bottom) agarose electrophoresis l = internal standard A = albumin ai =ai-globulin a2 = a2-glob-ulin, T = transferrin C = complement M = monoclonal band > = >-globulins X = marker). CE conditions capillary 30cmx 50 pm (ID), 9kV, detection at214nm. Separation buffer 7g boric acid, 7g sodium carbonate, and 5 g of polyethylene glycol 8000 in 1000 ml water.

Although the total B-cell population has been low due to the lymphopenia the 7oPBM s recognised as B cells remains normal, as have serum and secretory immunoglobulins. Immunoelectrophoresis has shown no monoclonal band. Sero-conversion to respiratory syncytial virus has been noted (litre 1/10,1/40,1/10 at 6,12, and 16 months respectively. The patient was immunised with diptheria and tetanus toxoid plus inactivated polio vaccine at 4,6 and 12 months. No polio antibodies were detected but following tetanus immunisation 1-2 units/ml tetanus antitoxin were produced. There has been no response to intradermal Candida antigen at 6,12, and 15 months of age. 

If a monoclonal band, or free light chains or heavy chains, are detected by IFBP, are they the pathogenic ones These abnormalities demonstrate a dysimmune milieu within the patient and a suspicion that the detected abnormality might be the cytotoxic one. However, conceptually the actual dysimmune cytotoxicity could be, qualitatively, due to a different monoclonal nano-farmly that is not quantitatively high enough above the detection threshold to be identified as "monoclonal."... 

Comment. A patient s IgG-kappa or other monoclonal band should o/be dismissed as "normal in aging," it is an important dysimmune parameter that is more common in aging bnt is not normal. The likelihood that the monoclonal immunoglobulin is the cause of a patient s nenromnscular disorder is based on clinical judgment. Carefnl and prolonged treatment is usually needed to achieve snmmated improvement, and avoid the Sisyphns phenomenon (see Chapter 2). 

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