Determination of tau proteins and beta-amyloic 42 in cerebrospinal fluid by ELISA methods and preliminary normative values
Abstract
Aim: The aim of the study was to compare ELISA methods for determination of triplet protein levels - total (t-tau) and phosphorylated tau (p-tau) proteins and beta-amyloid (A beta 42) (A beta 42) in cerebrospinal fluid (CSF) from manufacturers Fujirebio and EUROIMMUN; and to provide guidance for normal concentrations from cognitively healthy elderly people. Patients and methods: The group consisted of 38 cognitively healthy persons over 55 years of age (19 men) whose average age was 67 +/- 8 years.
In each CSF sample, we examined the protein triplet by both ELISA INNOTEST and EUROIMMUN AG kits. Results: A comparison of ELISA methods for determination of t-tau and p-tau proteins and A beta 42 using the Bland and Altman difference graph shows that the differences between methods, with the exception of isolated outliers, were within the range of compliance (mean +/- 1.96 SD).
Correlation coefficient values suggest significant agreement for t-tau protein assay kits. Based on our results and experience, we propose to classify CSF concentrations into three groups: 1. decreased; 2. questionable and borderline; 3. increased concentrations in ng/L based on our consensus as follows: t-tau protein , p181-tau protein and A beta 42.
Conclusion: ELISA kits from two producers are suitable for determination of the triplet proteins in CSF. Our results based on real measurements of samples of carefully selected and examined healthy elderly people from the Czech Republic or the norms based on our consensus recommendation can be used as reference range of the triplet.