A ZONE IMMUNOELECTROPHORESIS ASSAY-METHOD FOR QUANTIFICATION OF APOLIPOPROTEIN-D IN HUMAN CEREBROSPINAL-FLUID

A zone immunoelectrophoresis assay (ZIA) has been developed for the qu antification of apolipoprotein D (ape D) in human unconcentrated cereb rospinal fluid (CSF). The ape D concentrations of samples of the serum , plasma and CSF were directly proportional to the migration distances of the corresponding zones of immunoprecipitates developed during ele ctrophoresis in glass capillaries filled with antibody-containing agar ose gel. A linear standard curve, between about 1 and 12 mg of apo D/l was obtained using a commercial serum preparation, Seronorm(R), as ap o D standard. The coefficients of variation of the ZIA were below 8% ( n = 5 x 6) and 10% (n = 8) for within-run and between-run reproducibil ity, respectively, Quantification experiments with disulfide-reducing agent, mixtures of CSF and urine as well as frozen and stored CSF samp les indicated parallelism between the precipitate-forming immunologic reactions of ape D in different sample matrices when performed with ZI A. Application of this method to quantify apo D of CSF and plasma samp les from 51 normal healthy men aged 16-72 years yielded means +/- SD o f 5.3 +/- 1.5 mg/l and 128.4 +/- 22.7 mg/l, respectively. No correlati on was found between the CSF and plasma ape D concentrations.