A robust quantitative solid phase immunoassay for the acute phase protein C-reactive protein (CRP) based on cytidine 5′-diphosphocholine coupled dendrimers

C-reactive protein (CRP) is an important acute phase protein, being used as a sensitive indicator of inflammation and infection and is also associated with the risk of cardiovascular problems. The present paper describes a robust and sensitive ELISA for CRP, based on the affinity of CRP for phosphocholine. In this design synthetic globular polymers (dendrimers) are used as scaffolds for the multivalent display of phosphocholine molecules. CRP present in a sample binds to the phosphocholine moiety presented at high density in the coating layer and is detectable by specific antibodies. The ELISA was applied to determination of pig and human CRP using commercially available antibodies against human CRP. The assay was shown to be more sensitive than previously published immunoassays employing albumin-coupled cytidine diphosphocholine. The coating was stable for at least 30 days at room temperature and the assay showed high intra- and interassay reproducibility. Results were compared with an immunoturbidimetric method and with a commercial ELISA kit and there was very good agreement with the immunoturbidimetric method, however not with the commercial assay, probably due to a calibration discrepancy. The assay is applicable to other species by providing an adequate detection antibody having the desired species specificity.