Bence Jones protein

A Bence Jones protein is a monoclonal globulin protein found in the blood or urine, with a molecular weight of 22-24 kDa.

Finding this protein is often suggestive of multiple myeloma or Waldenstrom's macroglobulinemia.

Bence Jones Proteins are particularly diagnostic of multiple myeloma in the context of end-organ manifestations such as malignant bone marrow cancer, renal failure, lytic bone disease, or anemia, or large numbers of plasma cells in the bone marrow of patients. Bence Jones Proteins are present in 2/3 of multiple myeloma cases.

The proteins are immunoglobulin light chains (paraproteins) and are produced by neoplastic plasma cells. They can be kappa (most of the time) or lambda. The light chains can be immunoglobulin fragments or single homogeneous immunoglobulins. They are found in urine due to the kidneys' decreased filtration capabilities due to renal failure, often induced by hypercalcemia from the calcium released as the bones are destroyed. The light chains have traditionally been detected by heating or electrophoresis of concentrated urine. More recently serum free light chain assays have been utilised in a number of published studies which have indicated superiority over the urine tests, particularly for patients producing low levels of monoclonal free light chains, as seen in nonsecretory multiple myeloma and AL amyloidosis. This is primarily because of the re-absorption of free light chains in the kidneys, creating a "threshold" of light chain production which must be exceeded before measurable quantities overflow into the urine. As such, urinalysis is a fickle witness to changing free light chain production.

There are various rarer conditions that can produce Bence Jones proteins, such as Waldenström's macroglobulinemia and other malignances.

The Bence Jones protein was described by the English physician Henry Bence Jones in 1847 and published in 1848. The protein was later sequenced by Frank Putnam at the laboratory of Fred Sanger in Cambridge, who was the first to report the entire sequence.