Bound and free light chains in serum from patients affected with various neurological diseases.

Six immunological parameters, of which the most important are the quantitative distribution of the free light chains, and the kappa-lambda ratios of both bound and free light chains, were investigated in serum of patients affected with various neurological disorders and compared to controls. Subacute sclerosing panencephalitis and viral encephalitis, which are diseases characterized by hyperimmunisation against definite antigens, are accompanied by a considerable quantitative increase in free light chains; in subacute sclerosing panencephalitis serum there is an increase of both free kappa and lambda chains, whereas in viral encephalitis serum the increase of free light chains were restricted to lambda chains. There is a good correlation between the kappa-lambda ratio of, on the one hand, bound light chains and, on the other hand, free light chains for controls and subacute sclerosing panencephalitis; but in multiple sclerosis, amyotrophic lateral sclerosis and viral encephalitis, the ratios for bound light chains are totally different from ratios for free light chains. A general kappa increase, which we earlier reported for bound light chains in 16 cases of multiple sclerosis, was not confirmed by the investigation of an additional 26 cases: kappa decrease was also noticed in a considerable number of cases.