OBJECTIVETo establish a method that can quantitatively detect S100 protein in CSF, and evaluate the possibility in diagnosis of Creutzfeldt-Jakob disease (CJD).

METHODSS100 gene was amplified by PCR from a commercially supplied human brain cDNA library. After verified by sequence analysis, the full length of S100 DNA was subcloned into a (GST) expression vector Pgex-2T, and the expression of GST-S100 fusion protein was induced. Rabbits were immunized with the purified GST-S100 fusion protein, and the antiserum raised against S100 protein was collected and further evaluated. Using biotin-avidin system, a sandwich ELISA was established for quantitatively determining S100 protein, and further, used in screening for S100 protein in CSF and serum samples.

RESULTSSDS-PAGE assays yielded a roughly 35,000 GST-S100 fusion protein. Using the established method, three CSF samples from probable CJD patients (14-3-3 protein positive in CSF) showed higher concentration of S100 protein (higher than 2.900 microg/L), whereas other CSF samples collected from patients with other CNS diseases showed lower concentration of S100 (less than 0.180 microg/L).Moreover, the sera S100 proteins from all the collected samples showed distinct individual difference.

CONCLUSIONSThe established method can be used in determining S100 protein in CSF quantitatively. The feasibility and significance of S100 protein in CSF for diagnosis of CJD should be further considered with more CSF samples.