Quantitation of C-reactive protein in cerebrospinal fluid and serum by zone immunoelectrophoresis assay (ZIA).

The zone immunoelectrophoresis assay (ZIA) for C-reactive protein (CRP) determinations is easy to perform and requires only small amount of antiserum, e.g., 25-100 and 0.5-1.0 microliter anti-CRP antibody/20 serum and CSF samples, respectively. For quantitating CSF-CRP the immunoprecipitates formed were stained using alkaline phosphatase-conjugated secondary antibodies and the lowest standard concentration used was 30 micrograms/l. The immunoprecipitates formed when measuring CRP in serum were stained by Coomasie brilliant blue R250 with a detection limit of about 300 micrograms/l. CRP was determined in cerebrospinal fluid in 27 patients with bacterial meningitis (range less than 0.03-23.0 mg/l) and in 25 patients with viral meningitis (range less than 0.03-0.23 mg/l). CRP was quantitated in 52 sera by both the CRP ZIA method (y) and by electroimmunoassay (x). The correlation coefficient was r = 0.992 with the regression line y = 1.024 x + 0.855.