Description
Synonyms (rus): Bence-Jones protein, free light chains in urine
Synonyms (eng): Bence-Jones protein, free light chains kappa nad lambda in urine
Biomaterial: Single urine
Indicator(s): Bence-Jones protein
Method(s): Agarose gel electrophoresis, Immunofixation
Container type and preanalytical features: Urine preservative tube, 8 ml
Free monoclonal light chains of immunoglobulins in the urine are called Bence Jones protein. Bence Jones proteinuria is a variant of prerenal proteinuria, which is caused by excess protein in the blood plasma. Detection of a paraprotein in urine (Bence Jones protein) during a screening test of a urine sample using immunofixation indicates a monoclonal gammopathy. The most likely presence is those forms of gammopathies that are accompanied by the secretion of free light chains of immunoglobulins (light chain disease, other forms of myeloma, MGUS with paraprotein in the urine, etc.). At the same time, light chains have a nephrotoxic effect, so over time, depending on the level of damage to the nephron, glomerular or tubular proteinuria may occur. In rare cases, paraprotein in urine may be represented not by free light chains, but by intact paraprotein (whole molecules of monoclonal immunogloblin), i.e. is not a Bence Jones protein by definition.
BENCE JONES PROTEIN
BENCE JONES WHITE
K (H. Bence-Jones, 1813-1873, English physician; synonym:
Bence-Jones protein body, Bence-Jones albumin
) is a urine protein that appears in it under certain pathological conditions. It has the property of precipitating when heated to a temperature of 50-60°, dissolving when heated to temperatures close to the boiling point of the solution, and precipitating again when cooled. By these properties, proteinuria with the presence of Bence-Jones proteins in the urine (Bence-Jones proteinuria) can be distinguished from other types of proteinuria (see), since otherwise it gives all the characteristic reactions to proteins. First described in 1848 by Bence-Jones. The appearance of protein in Bence-Jones's urine is a characteristic symptom of multiple myeloma (see). Bence Jones proteins are light chains of immunoglobulins (see) produced by myeloma cells; molecular weight is about 22 thousand (dimers - in the range of 40-44 thousand). In each individual case of myeloma, meloma proteins and, accordingly, light chains are monoclonal antibodies, that is, homogeneous proteins synthesized by one clone of plasma cells. On the other hand, different patients may have many different Bence Jones proteins belonging to the class of immunoglobulin light chains. Accordingly, the amino acid composition and dietary amino acids of Bence Jones protein isolated from the urine of patients with multiple myeloma are not always the same. Characteristic of Bence Jones protein is the absence or very low content of methionine, histidine, hydroxyproline and high tyrosine content. Bence Jones protein crystallizes easily; Cases of its spontaneous crystallization in urinary tubules and tumors (protein crystals) have been described.
To detect Bence Jones protein in urine, the urine is acidified to a pH of about 5.5, filtered, and heated. Characteristic is the precipitation of the protein at a temperature of about 56°, an increase in the sediment upon further heating to complete dissolution at boiling (Bence-Jones test). To quantify Bence-Jones protein, urine is heated to t° 70°, the protein precipitate is separated by centrifugation, washed with water, alcohol, ether and weighed.
Bence Jones protein is found in the urine of 30-80% of patients with multiple myeloma. The appearance of this protein in the urine has also been described in some cases of leukemia, lymphosarcoma, osteomalacia and a number of other diseases, but currently the appearance of Bence-Jones protein in the urine is considered as an important specific diagnostic symptom of multiple myeloma, also allowing the possibility of its appearance in the urine only in rare cases. cases of extensive bone marrow lesions (eg, myeloid leukemia). The Bence Jones protein content in urine can range from a fraction of a percent to 6-7%; Cases of patients with multiple myeloma excreting up to 50 g of this protein per day have been described. Bence Jones proteinuria is usually accompanied by hyperproteinemia, which is attributed to the presence of myeloma proteins in the blood plasma. Bence Jones protein appears to be produced by myeloma cells.
Bibliography:
Bence-Jones protein and blood proteins in multiple myeloma, in the book: Sovrem. problem onkol., trans. with in., ed. A. II. Serebrova, V. 3(30), ser. B, p. 82, M.. 1952; Gulevich V.S. A rare case of finding protein crystals in ovules, Zhurn. let's experiment biol, i med., vol. 5. D1 15, p. 215, 1927, bibliogr.; Basch N. An introduction to the biochemistry of the cancer cell, p. 269, NY— L., : >62; L ichtwitz L. Klinische Chemie "8. 145, V., 1930; Polonovskl M. et D e 1 b a g e F. Les pro t6 Ines de Bence-Jones, in the book: Ekhrovev annuels biochim. möd., sous la dir. de M. Polonovskl ea, J. 257, P., 1951; Putnam FW Aberra-ona of protein metabolism in multiple myeloma. Physiol. Rev., v. 37, p. 512, 1057.
N. B. Zversky.
Interpretation
The absence of paraprotein (M-gradient) in the urine most likely excludes the diagnosis of paraproteinemia, accompanied by the synthesis of a free light chain, but does not exclude the presence of paraprotein in the blood serum. Detection of a paraprotein in urine (Bence Jones protein), using polyclonal antiserum, during a screening test of a urine sample indicates a hematological malignancy. Urinary paraprotein typing using immunofixation with a panel of antisera may be recommended.
Reasons for deviations
Most often, Bence Jones protein in urine is a sign of myeloma. This is a malignant bone marrow tumor that consists of plasma cells. This pathology can be asymptomatic for a long time. And only urine analysis helps to identify this dangerous disease in its early stages.
Bence Jones protein can also be determined in other diseases:
- Waldenström's disease (bone marrow tumor consisting of lymphocytes);
- idiopathic amyloidosis (a disorder of protein metabolism in which proteins and polysaccharides accumulate in tissues);
- osteosarcoma (a progressive malignant tumor of bone tissue);
- lymphogranulomatosis (malignant proliferation of lymphoid tissue);
- lymphocytic leukemia (a malignant neoplasm that affects the spleen, bone marrow and lymph nodes);
- endotheliosis (pathological changes in the walls of blood vessels).
A small amount of this type of protein is detected in the analysis of monoclonal gammopathy. This disease is characterized by increased secretion of pathologically altered immunoglobulins. It is assessed as a precancerous condition of the bone marrow.
Bence Jones proteinuria
The definition of Bence-Jones proteinuria, first of all, indicates multiple myeloma. This tumor is malignant in nature, but is not cancer, since it does not originate from tissues, but from plasma cells. The disease has three forms:
- diffuse, damaging the bone marrow;
- diffuse-focal, affecting the bone marrow and some other organs (in particular, the kidneys);
- multiple myeloma, which affects the entire body.
Myeloma is characterized by excessive bone fragility, frequent fractures, and bone pain. The disease spreads to the renal apparatus, the patient quickly develops myeloma nephropathy, which leads to renal decompensation.
What does He4 mean in a blood test + norms
In addition to myeloma, detection of Bence Jones protein in urine can be a sign of the following pathologies:
- Fanconi syndrome and renal amyloidosis are diseases characterized by impaired protein metabolism;
- malignant disease of lymphatic tissue, spleen, liver, lymph nodes (lymphocytic leukemia);
- tumor of the hematopoietic and lymphatic system (lymphosarcoma);
- new bone formation, with early manifestation of metastases throughout the body (steosarcoma);
- damage to plasma cells (plasmocytoma);
- malignant degeneration of the endothelium of blood vessels (endotheliosis);
- systemic pathological process associated with impaired mineralization of bone tissue (osteomalacia);
- oncology of lymphoid tissue (lymphogranulomato);
- malignant tumor of the hematopoietic organs (Waldenström macroglobulinemia).
To accurately confirm each of the possible diagnoses, a single urine test for Bence Jones protein is not enough. The patient needs a comprehensive examination.
Indications for the study
A urine test for Bence Jones protein is a specific test that is not carried out in every laboratory. A referral to donate urine is issued by an oncologist or urologist if the patient has symptomatic complaints that correspond to signs of one of the possible oncological pathologies.
The study is prescribed for a diagnosed disorder of protein-carbohydrate metabolism with extracellular deposition in the renal tissue of a complex protein-polysaccharide compound (amyloid) - amyloidosis disease of the renal apparatus.
On a regular basis, analysis is taken from patients with malignant lesions of the bone and lymphatic system to monitor the dynamics of therapy. In addition, the study is recommended for people with an unfavorable family history (oncological diseases in the listed body systems).
Norm
The urine of a healthy person contains a small amount of protein - 0.033 g/l. A slight abnormality, called transient protein, is present in the body of newborns. Organic matter levels return to normal within a few days.
The excess protein indicator in children aged 12-13 can reach 0.01 g/l. Changes in the composition of children's urine are provoked by the child's activity and intense physical activity. In medical practice, the phenomenon is called orthostatic proteinuria.
The urine of a healthy person contains a small amount of protein
The presence of Bence-Jones protein is not considered a pathology if its formation is explained by organ transplantation or treatment with cytotoxic drugs. In all cases, protein sediment in the urine is a symptom of diseases - chronic leukemia, Waldenström's macroglobulinemia, myeloma. These pathologies are characterized by an increase in the amount of the substance to 0.02 g/l.
Causes
Excessive amounts of Bence Jones protein are recruited by cells that are responsible for producing antibodies. Once in the bloodstream, the substance moves throughout the body, settles in the kidneys, and then comes out through urination.
Protein sediment in the urine occurs in diseases:
- Myeloma is a malignant tumor that develops in the bone marrow and causes problems with the circulatory system.
- Plasmacytoma is a neoplastic disease that provokes the destruction of bone tissue.
- Primary Amyloidosis is a pathology that is characterized by improper protein metabolism in the body.
- Chronic leukemia is a cancer that damages the lymphatic system, liver, and bone marrow.
- Osteosarcoma is a malignant tumor that affects bone tissue. A feature of the disease is the formation of metastases in the early stages.
Late diagnosis of pathologies and lack of treatment can lead to serious consequences.
How to take a urine test for Bence Jones protein
Testing urine for Bence Jones protein is a difficult test. Testing urine for Bence Jones protein involves a number of complex procedures, so laboratory technicians need a properly collected sample.
General rules for collecting urine to determine Bence Jones protein:
- a week before the test, reduce the consumption of liver and meat;
- the day before the test, exclude carbonated water and drinks, alcohol, brightly colored fresh vegetables and fruits, sometimes the doctor will recommend stopping taking certain medications;
- Prepare a container for collecting urine in advance. This can be a disposable pharmacy container that does not need to be processed or a glass jar with a metal lid after rinsing with boiling water;
- Before collecting urine, wash your genitals without soap or detergents;
- collect an average portion of morning urine with a volume of at least 50 ml (when urinating for the first time after waking up, the first portion of urine should be poured into the toilet, then the main portion should be collected in a container, and finish urinating not in a jar);
- seal the container hermetically and deliver it to the laboratory within a maximum of two hours (the time can be extended if the collected urine is cooled).
