Serum Monoclonal Component Research Articles

Kappa/lambda index for confirming urinary free light chain in amyloidosis AL and other plasma cell dyscrasias

Primary systemic amyloidosis (AL), a disease involving the deposition of immunoglobulin light chains in tissue, is caused by a plasma cell dyscrasia. In the case of amyloidosis reported here, no monoclonal component was seen upon routine protein electrophoresis of serum or urine nor was a bone marrow analysis positive for AL. Immunofixation electrophoresis did not show a typical paraprotein band but did show, in the gamma region, two large diffuse bands and a lower concentration of oligoclonal-type bands, all of which stained for free lambda but not for free kappa chain. The ratio of kappa to lambda chains in urine was 0.178, much less than the ratio in serum (1.3). Six other urine samples from a group of patients with documented Bence Jones proteinuria also exhibited kappa/lambda ratios that differed manyfold from the ratios in their corresponding serum samples. On the other hand, the kappa/lambda ratios from seven controls (seven patients with generalized proteinuria unrelated to plasma cell dyscrasia) were similar in serum and urine. This difference between the kappa/lambda ratios from serum and urine can be expressed as a kappa/lambda index. The index was significantly different (P less than 0.01) between the two patient groups compared here, and was useful in confirming the presence of Bence Jones protein in this case with a difficult-to-interpret electrophoretic pattern. Although the kappa/lambda ratio has been widely used for confirmation and identification of monoclonal components in serum, its use in clinical laboratories has not been widely extended to urine. Comparison of serum and urine kappa/lambda ratios as a kappa/lambda index may help reduce the need for more complex immunoelectrophoresis techniques in identifying free light chains in urine.

Serum protein electrophoresis: Italian survey 1986.

In 1986 the Protein Commission of the Italian Society of Clinical Biochemistry (SIBIOC) carried out its second survey on the use of serum protein electrophoresis in Italian laboratories. Three serum samples plus a questionnaire were sent to the 253 laboratories which agreed to take part. The three samples had the following characteristics: Serum 1: a 60 g/L IgM-lambda monoclonal component (MC); Serum 2: an artificially split alpha-2 zone; Serum 3: a very faint lambda chain MC. These features were chosen to assess (a) the type of report; (b) the resolution quality of the electrophoretic technique; and (c) the laboratory capacity to detect a small MC. The most significant features revealed by the survey were: (a) the poor capacity of assessment of the small MC in Serum 3 (only detected by 23.1% of laboratories); (b) the discouraging tendency to delegate electrophoretic diagnostic interpretation to ward physicians (44.4% of participating laboratories provided only densitometric values and graphs).

Light Chain Nephropathy: Histological and Clinical Aspects in 15 Cases

Fifteen patients aged 31-74 years (five male, ten female) on renal biopsy showed intense linear deposits of light chains along tubular basement membranes (TBM) by immunofluorescence, and/or granular dense deposits on electronmicroscopy. Multiple myeloma was diagnosed in ten patients. The onset of myeloma and nephropathy was simultaneous in six patients; nephropathy preceded or followed the diagnosis of myeloma in three and one patients respectively. The mode of onset of nephropathy was acute or rapidly progressive renal failure in five cases, chronic renal failure in seven, and heavy proteinuria in three. Only two patients had normal renal function at biopsy. Serum monoclonal component was kappa in five patients, IgG kappa in three, IgD kappa in one, IgG lambda in one, IgA lambda in one, absent in three, and not detected in one. On light microscopy eight cases had nodular glomerulosclerosis, three cast nephropathy and 14 TBM thickening. Immunofluorescence for monoclonal light chain(s) was positive in 11 of 13 cases. Electron microscopy showed finely granular deposits in the inner side of glomerular basement membranes (GBM) and the outer side of TBM in 11 of 11 tested cases. The evolution was towards chronic renal failure in 12 patients (six of whom required dialysis), death in two, unknown in one. Four patients died after a period of dialysis, from infections or cardiovascular complications.

Immune disorders in agnogenic myeloid metaplasia: relations to myelofibrosis

Summary. Tests for a dysimmune state were done in an unselected group of 67 patients with agnogenic myeloid metaplasia (AMM). The results were compared to those of 56 patients with polycythaemia vera (PV). 75% of AMM patients versus 32% of PV patients had various abnormalities. The most frequent disorders among AMM patients were serum antinuclear and anti smooth muscle autoantibodies (10 3% each), a positive test for rheumatoid factor (21 7%), a polyclonal increase in serum immunoglobulin levels (46 8%) or a serum monoclonal component (9 7%), a positive direct Coombs’test (19%), an anti I autoantibody (30%). In AMM patients there was no relationship between age, sex, importance of splenic enlargement, time from diagnosis or treatment and the present of a dysimmunity.Furthermore, in AMM patients, but also in PV patients, it seems that the more frequent and numerous these abnormalities the more severe is the myelofibrosis. Like other previous studies, these results suggest a lymphoid cell involvement in AMM and a role for these immune disorders in the pathogenesis of myelofibrosis.

Myeloma Protein Kinetics Following Chemotherapy

The effects of chemotherapy were evaluated in 43 multiple myeloma patients with high monoclonal globulin levels in both serum and urine. In responding patients, Bence Jones protein excretion declined more rapidly and markedly than the serum myeloma protein. Bence Jones protein excretion was reduced by 50% within 2 mo in responders, remained unchanged in nonresponders, and declined with a slow halving time of 2-7 mo in patients with partial disease control. Three patients with clinical resistance to treatment showed atypical protein changes and progressively more Bence Jones protein excretion relative to their serum monoclonal component. Serial measurements of Bence Jones protein excretion provided an early and reliable index of tumor mass change in patients with multiple myeloma.

Myeloma protein kinetics following chemotherapy

The effects of chemotherapy were evaluated in 43 multiple myeloma patients with high monoclonal globulin levels in both serum and urine. In responding patients, Bence Jones protein excretion declined more rapidly and markedly than the serum myeloma protein. Bence Jones protein excretion was reduced by 50% within 2 mo in responders, remained unchanged in nonresponders, and declined with a slow halving time of 2–7 mo in patients with partial disease control. Three patients with clinical resistance to treatment showed atypical protein changes and progressively more Bence Jones protein excretion relative to their serum monoclonal component. Serial measurements of Bence Jones protein excretion provided an early and reliable index of tumor mass change in patients with multiple myeloma.

Clinical and immunochemical studies of 20 patients with amyloidosis and plasma cell dyscrasia.

Amyloidosis associated with plasma cell dyscrasia (AAPCD) is a relatively rare clinical entity (4% of our patients with PCD) and its early recognition and distinction from multiple myeloma (MM) may be of great therapeutic and prognostic significance. Laboratory parameters, such as concentrations of normal polyclonal Ig, Bence-Jones proteins and serum monoclonal components (MC) showed in our patients lower MC concentrations than in MM, lambda-L-chains and of gamma-H-chains predominating. Sequential skeletal X-ray studies and bone marrow morphology remain essential diagnostic procedures. Due to the lack of efficient therapeutic agents for AAPCD and the great progress achieved in recent years in the treatment of secondary amyloidosis, the immunochemical analysis of the isolated amyloid fibril as well as of the surrounding 'ground substance' should be pursued in AAPCD. Our data support previous observations, that in AAPCD the amyloid fibril subunit is an L-chain fragment predominantly derived from lambda-L-chains which originates from the same clone as the MC. The localization of an enzymatic cleavage point on the L-chain, the detection of a specific proteolytic enzyme and the identification of additional components in the amyloid substance, may further elucidate the etiopathogenesis of AAPCD.