Biosynthesis and characterization of intracellular IgDkappa in a case of CLL

A case of chronic lymphocytic leukaemia (CLL) with diffuse intracellular IgDkappa is reported. No serum paraprotein or urinary Bence-Jones protein were detected. No surface immunoglobulin was found on the neoplastic lymphocytes, but the cells had receptors for Fcgamma and the C3 component of complement consistent with other cases of CLL. Biosynthetic studies confirmed that the cells synthesized IgDkappa but there was no evidence for secretion of IgD into the culture medium. The cells did not produce Ig of any other class. The intracellular IgD occurred predominantly as deltakappa units with no covalent links between the chains. These findings are discussed.