Bence Jones proteins are identical to which immunoglobulin chains?

Bence Jones proteins are identical to which immunoglobulin chains?

• A. H chains
• B. L chains
• C. IgM molecules
• D. IgG molecules

Answer: (B)

Bence Jones proteins are the free immunoglobulin light chains produced by malignant plasma cells. They are identical to the light chain portion of antibodies (the L chains) and are excreted in urine when produced in excess. They come in two types, kappa and lambda, just like normal light chains. They are not heavy chains, and they are not whole immunoglobulin molecules like IgM or IgG; those are complete antibodies, whereas Bence Jones proteins are only the light chains shed into urine. This is why the correct identification is the light chains.

Bence Jones proteins are the free immunoglobulin light chains produced by malignant plasma cells. They are identical to the light chain portion of antibodies (the L chains) and are excreted in urine when produced in excess. They come in two types, kappa and lambda, just like normal light chains. They are not heavy chains, and they are not whole immunoglobulin molecules like IgM or IgG; those are complete antibodies, whereas Bence Jones proteins are only the light chains shed into urine. This is why the correct identification is the light chains.