Free light chains in the cerebrospinal fluid: an indicator of recent immunological stimulation.

A group of 38 patients with immunoglobulin free light chains (kappa and/or lambda) in the cerebrospinal fluid was studied. Only five of them showed one band of kappa free light chains, 36 of them showed one or more bands of lambda free light chains. There were 33 multiple sclerosis patients among them and they were compared with 33 control multiple sclerosis patients who did not have free light chains but only showed an oligoclonal pattern of immunoglobulins in their CSF. Of several clinical and pathological parameters, only three were statistically significant: (A) for all patients, as well as for the multiple sclerosis patients alone, elevated numbers of free light chains of type lambda were associated with the elevated numbers of white blood cells in the CSF (p less than 0.003), (B) for multiple sclerosis patients, elevated numbers of free light chains of type lambda were associated with associated with shorter time intervals between the last relapse and the date of the lumbar puncture (p less than 0.004) and (C) also with shorter duration of the disease (p less than 0.01). The presence of lambda free light chains in the cerebrospinal fluid seems to indicate that recent antigenic stimulation has occurred within the central nervous system following exacerbation. The inverse association of the number of lambda free light chains with the duration of the disease is suggestive of a pathological expression of the "burning out" phenomenon of the multiple sclerosis process.