Immunofluorescence determination of IgG in cerebrospinal fluid following high performance liquid gel permeation...

A simple technique using high performance liquid gel permeation chromatography for determination of IgG in cerebrospinal fluid (CSF) is described. Accurate determination of IgG was achieved by precolumn derivatization with fluorescein isothiocyanate-conjugated anti-human IgG Fab, a substance that readily yields a fluorescent immune complex. Immune complexes separated as a well-delineated peak in the column void volume, and were measured by the fluorescence of the column eluates (Ex = 490 nm, Em = 520 nm). The results were reproducible with a deviation of less than 2% and a good linear relationship over the range of 2.0-24.5 mg/dl. The IgG concentration assayed by the column method correlated well with values obtained by laser nephelometry.