The paper deals with examination of free kappa light chains (FKLC) in the cerebrospinal fluid and serum of patients with multiple sclerosis (MS). The patient group included 84 women (mean age 34.03 ± 10.33 years) and 24 men (mean age 33.81 ± 10.61 years). The average disease duration was 8.04 ± 7.59 years for women and 7.59 ± 7.07 years for men. Quantitative determination was performed with ELISA, proof of oligoclonality with isoelectric focusation followed by immunoblotting. The proportion of intrathecally synthesized FKLS was determined using the FKLC quotient (QFKLC = CSFFKLC / serumFKLC) and FKLC index (QFKLC / Qalbumin). FKLC results were correlated with clinical parameters as well as biochemical ones. The presence of FKLC was detected in 102 of 110 examined cerebrospinal fluid samples, there is a significant correlation between the number of oligo FKLC and positivity of oligo-IgG. Examination of free kappa light chains can be recommended in cases of clinical suspicion for MS, when the oligoclonal IgG examination is negative.

        Key words: free kappa light chains, multiple sclerosis, cerebrospinal fluid