Multiple clonally-restricted immunoglobulins in human sera: disease associations

Diseases associated with multiple clonally-restricted serum immunoglobulin (Ig) abnormalities present at levels which, in most cases, preclude detection by conventional immunoelectrophoresis, were studied using methods for detection and characterization of homogeneous Ig that are approximately equal to 40 times more sensitive than either cellulose acetate zone electrophoresis or immunoelectrophoresis. Patients with these Ig abnormalities had a high incidence of infectious disease (29% of total cases), malignancy (19%), connective tissue disease (14%) and liver disease (10%). The concentration of individual clonal products was found to wax and wane, but it could not be determined whether these clonally-restricted Ig species represent, wholly or in part, the products of dominant antibody-producing plasma cell clones involved in the patients' response to their disease. We conclude that multiple homogeneous serum Ig abnormalities occur in clinical situations where heightened antigenic stimulation and/or immune reactivity are thought to occur (e.g., infections, malignancies and autoimmunity). Laboratory evaluation of these Ig abnormalities could be useful for diagnostic and/or therapeutic monitoring purposes in situations where the specificity of the clonally-restricted Ig species can be established.