Synthesis of Abnormal Heavy Chains in Bence-Jones Plasma Cell Leukemia With Intracellular IgG

In a patient with plasma cell leukemia and a k type Bence Jones protein in serum and urine, the immunofluorescence study of blood plasma cells showed intracellular y and k chain determinants. Biosynthesis experiments showed the production of abnormally short heavy chains (45,000 daltons) that assembled with normal sized light chains with a partial block. These abnormal heavy chains were secreted at a slow rate and were degraded after secretion.