Index of light kappa/lambda and lambda/kappa chains in monoclonal gammopathies.

Concentrations of the light chains kappa and lambda were determined by simple radial immunodiffusion in the blood sera of 437 patients with monoclonal gammopathies. The kappa/lambda index was calculated in monoclonal gammopathies with the antigenic type of kappa light chains, while in monoclonal gammopathies with the antigenic type of lambda light chains the lambda/kappa index was calculated. The results obtained in malignant monoclonal gammopathies were compared with the results obtained in monoclonal gammopathies of undetermined significance for IgG and IgM paraproteinemias. Differences of high statistical significance were established (for IgG and IgA p less than 0.001, for IgM p less than 0.005) and thus the light-chain index can be used as another marker in differential diagnosis of monoclonal gammopathies.