Intrathecal kappa free light chains as markers for multiple sclerosis

Area of Science:

• Neurology
• Immunology
• Biochemistry

Background:

• Intrathecal IgG synthesis is crucial for diagnosing multiple sclerosis (MS).
• The cerebrospinal fluid (CSF) kappa free light chain (KFLC) index is a potential marker for this synthesis.
• Different interpretation methods for KFLC require comparison for optimal diagnostic and prognostic use.

Purpose of the Study:

• To compare the diagnostic efficiency of KFLC using various interpretation approaches in MS.
• To assess the prognostic value of KFLC in radiologically and clinically isolated syndromes (RIS-CIS).

Main Methods:

• Analyzed CSF and serum samples from 133 MS patients and 240 with other neurological diseases.
• Measured albumin, lambda free light chain (LFLC), and KFLC using nephelometry.
• Calculated KFLC index, LFLC index, IgG index, and CSF ratios (KFLC/LFLC, KFLC/IgG, LFLC/IgG).

Main Results:

• KFLC levels were significantly higher in MS patients compared to controls.
• KFLC index and CSF KFLC/IgG ratio demonstrated high sensitivity and moderate specificity for MS diagnosis.
• Elevated KFLC index and CSF KFLC/IgG were observed in RIS-CIS patients who later converted to MS.

Conclusions:

• KFLC markers, particularly the KFLC index and CSF KFLC/IgG ratio, are accurate in diagnosing MS.
• These KFLC markers possess prognostic value in individuals with early MS syndromes (RIS-CIS).
• A "kappa-oriented" response is a hallmark of MS and impacts prognosis in early disease stages.