Free fragments of gamma chain in the urine. A possible source of confusion with gamma heavy-chain disease.

Abstract

With currently used microconcentrators, high-resolution electrophoresis, and immunofixation electrophoresis, relatively homogeneous free fragments of gamma chain (FFGC) unaccompanied by light chains, which cannot be found in the serum, may be discovered in the alpha-2 region during routine examination of the urine. The urinary alpha-migrating FFGC is of no apparent clinical significance and should not be confused with the antigenically related FFGCs of gamma heavy-chain disease. In gamma heavy-chain disease, the FFGCs are often demonstrable in the urine, but are always present in the serum and migrate in the beta-gamma region.