Bence-Jones protein

The urine of a healthy person does not contain the Bence-Jones protein, which is represented by light chains of immunoglobulins that are detected as a result of the formation of malignant tumor processes.

Laboratory studies for the presence of a specific low molecular weight protein are necessary in diagnosing a number of pathological conditions (more often problems of the β-system of immunity), and also in order to determine the effectiveness of the therapy used.

In an overabundance, the Bens-Jones protein is produced by plasma cells, moves with blood flow, and is excreted by urination. It is the latter property of protein bodies that allows one to suspect the following diseases when examining urine:

• myeloma;
• osteosarcoma;
• plasmacytoma;
• lymphocytic leukemia in chronic stage;
• lymphogranulomatosis;
• amyloidosis of primary type;
• macroglobulinemia;
• and idiopathic monoclonal gammopathy.

Clinically confirmed the relationship between the release of a specific protein and subsequent impairment of kidney function, due to the toxic effect of protein bodies on the epithelial structures of the kidney tubules, which in turn causes the phenomenon of dystrophy, Fanconi syndrome, renal amyloidosis.

[1], [2], [3], [4], [5], [6], [7], [8], [9]

Bens-Jones protein in the urine

The presence of protein in urine is called proteinuria. By prerenal proteinuria is understood the content in the urine of a large number of low-molecular protein. At the same time, there is no damage to the renal filter and tubules, and the normal functioning of the kidneys is not capable of providing reabsorption of protein bodies. Extracorporeal (false) proteinuria, i.e. Which proceeds without disturbance of renal function, indicates the presence of an infectious or malignant process in the body. Proteinuria is noted in 60-90% of cases of myeloma patients. About 20% of the pathological conditions occur on the myeloma of Bence-Jones.

The Bens-Jones protein in the urine is differentiated due to the humoral shifts of the β-system of immunity. The appearance of protein bodies is associated with myeloma pathology, paraproteinemic hemoblastoses, endotheliosis, Waldenstrom macroglobulinemia, lymphatic leukemia, osteosarcoma. Identification of the Bens-Jones protein in urine is an important diagnostic and prognostic stage. Bens-Jones protein in view of the low molecular weight is excreted in the urine, damaging the epithelium of the kidney tubules, which is fraught with the development of renal failure, which can lead to death. Important also is the timely classification of the protein in accordance with the type: λ-protein has a greater nephrotoxic effect than κ.

[10], [11], [12], [13], [14]

Analysis for Bens-Jones protein

The presence of protein bodies other than serum in urine indicates lymphatic leukemia, osteosarcoma or myeloma (bone marrow tumor processes). The Bence-Jones protein when the urine filtrate is heated to 45-60 ° C falls in the form of a cloudy sediment settling on the walls of the tube. Further increase in temperature to the boiling point dissolves the isolated turbidity.

The quantitative analysis for the Bens-Jones protein is as follows:

• use of a portion of water and part of nitric acid as a reagent;
• Placement in a tube of nitric acid (0.5-1ml) with layering the same level of urine under study;
• evaluation of the result after 2 minutes (the appearance of a thin ring at the boundary of liquid media indicates the presence of 0.033% of protein bodies).

Observation of a threadlike ring requires the dilution of urine with water in a ratio of 1: 1, the appearance of a thick ring indicates the need to mix a part of the urine with three parts of water, and in the case of a compact ring, the portion of urine is diluted with seven portions of water. And the breeding is continued until the characteristic sediment manifests itself in the 2-3-minute testing.

The amount of protein contained is calculated by multiplying 0.033% by the amount of dilution. For example, the urine was diluted 10 times, the ring of protein bodies appeared at the end of the third minute of the study, then the percentage inclusion of the protein was calculated as: 0.033x10 = 0.33.

In the absence of precipitation, assess the degree of turbidity - pronounced, weak or barely discernible traces of turbidity.

[15], [16], [17], [18], [19],

Secretion of the Bence-Jones protein

By the type of secreted immunoglobulin are distinguished:

• pathology of the light chains (secretion of the Bence-Jones protein);
• glomerulopathy (secretion of other immunoglobulins).

There are also various combinations of kidney damage. As practice shows, nephropathy is a consequence of lymphoproliferative pathology (multiple myeloma, chronic lymphocytic leukemia, Waldenstrom's disease, etc.).

Isolating into the bloodstream, like all proteins with a mass of molecules up to 40 kDa, light chains pass the renal filter, then through lysosomes break down into oligopeptides and amino acids. The excess of light chains provokes dysfunction of the catabolism reaction and the possible release of lysosome enzymes, which entails necrosis of the tubular tissues. Proteins cause inability to reabsorb, and when monoclonal light chains are connected to the Tamm-Horsfall protein, protein cylinders form in the distal tubules.

Bence-Jones protein in myeloma

By multiple myeloma is understood a pathological condition, when the body replaces full-fledged lungs with light immunoglobulin chains. Diagnosis of the disease and monitoring of the condition are carried out by laboratory examination of urine showing the quantitative content of protein bodies. The concretization of myeloma subtype is based on serum analysis. Clinical signs of the disease include: painful bone syndrome, dysfunction of urination, hematomas of unknown origin, fluid retention in the body.

Bence-Jones protein in myeloma is detected on the basis of standard testing, which shows the quantitative content of protein bodies and assesses the degree of kidney damage. Identification of the protein in the urine explains the damage to the epithelium with sclerosis of the renal stroma, eventually forming a renal failure - a common cause of death as a result of myeloma damage (the Bens-Jones protein completely clogs the tubules, preventing urination).

Statistics indicate that myeloma is differentiated in men over 60 years of age who have a history of genetic predisposition, obesity and immunosuppression, and who have been exposed to toxic and radioactive substances.

[20], [21], [22], [23], [24],

Determination of the Bence-Jones protein

To differentiate a specific protein, a laboratory study of the average portion of the morning urine is performed (a volume of at least 50 ml is required). The presence of the Bence-Jones protein with the determination of the quantitative component is possible by the immunofixation method. Separation of proteins occurs by means of electrophoresis followed by immunofixation with the help of special sera. When binding the protein to the antibodies of the lungs and heavy chains of immunoglobulins, immune complexes that are evaluated by staining are formed.

It should be noted that even the minimum protein concentration is detected due to the precipitating reaction to the acid sulfosalicylic. The Bens-Jones protein is determined by combining the filtered urine (4 ml) with acetate buffer (1 ml). Subsequent heating to 60 ° C in a water bath and holding for 15 minutes with a positive sample gives a characteristic precipitate. This technique is considered to be the most reliable. Negatively affect the results of the analysis can be excessively acidic or alkaline environment and low relative density of urine.

Research methods in which the Bens-Jones protein dissolves as a result of heating to 100 ° C or precipitated again during cooling are unreliable, since not all protein elements have the corresponding characteristics. But the use of indicator paper is absolutely not suitable for detecting the Bence-Jones protein.

[25], [26], [27], [28], [29], [30]