CEREBROSPINAL-FLUID FREE KAPPA-LIGHT-CHAINS VERSUS IGG FINDINGS IN NEUROLOGICAL DISORDERS - QUALITATIVE AND QUANTITATIVE MEASUREMENTS

In this study free kappa light chains in cerebrospinal fluid (CSF) wer e determined both by an affinity mediated capillary blotting technique after isoelectric focusing (IEF) in agarose gel and by a quantitative enzyme linked immunosorbent assay (ELISA). The free kappa results wer e compared with the IgG findings in 4 neurological patient groups with a distinct CSF IgG pattern: (1) CSF without oligoclonal IgG bands, (2 ) CSF with serum derived IgG bands, (3) CSF restricted IgG bands and ( 4) CSF restricted and serum derived IgG bands. Oligoclonal free kappa bands are nearly absent in CSF of groups 1 + 2, and present in 88% of group 3 and 84% of group 4 patients. We could also establish free kapp a indices from specimens in the 4 groups in analogy to IgG indices. Gr oup 1 had a median free kappa index of 1.1, group 2: 1.0 and groups 3 + 4: 10.0. The correspondence between immunoblot and index findings fo r free kappa is better than for IgG. Free kappa index is more sensitiv e but somewhat less specific than IgG index for establishing intrathec al immune production.