Helica Biosystems, Inc. produces CRP ELISA kits for the measurement of plasma/serum C-reactive protein (CRP) from a number of different species including human, rat, mouse and dog. While the rat and mouse kits are highly specific, in my experience, the canine kit exhibits some cross-reactivity with other mammalian species (such as seals). The kits come in two detection formats: 1) antibody and 2) C-polysaccharide. I have used both formats to detect rat CRP and have obtained similar results, suggesting that either format is suitable for reliable measurement of rat CRP. Furthermore, using an extraction protocol we developed in our lab, we have also used the rat CRP kits to reliably and repeatedly measure urinary CRP fragments. While the product insert mentions that the kit can be used for the detection of CRP in urine, to the best of our knowledge and capabilities, this was only accomplished following extraction of the CRP fragments in the urine. Nonetheless, our ability to modify the assay to fit our purposes demonstrates the kits flexibility to comply with the needs of the lab, which we found to be very beneficial.
All kits are supplied with all the necessary components/reagents to complete the assay including a 96-well microplate (either antibody or C-polysaccharide coated) and a vial of concentrated standard that needs to be diluted. The kit does not supply the reagents or extraction columns to extract urinary CRP, but these are readily available. The kit insert also does not provide information on a suggested extraction protocol. This needs to be developed separately. For plasma/serum and other media (except urine) samples need to be diluted prior to assay, and new users will need to run some test assays to determine the appropriate dilutions for their needs; however, suggested starting dilutions are provided. While the assay instructions only suggest the use of 4 standards ranging from 1.5 – 40 ug/ml for the canine CRP kit and 6 for the rat CRP ranging from 1.6 – 133 ng/ml, we have improved the reliability and reproducibility of our results by simply serially diluting the highest standard 7 times, going beyond the lowest suggested standard. The limit of detection for the canine kit is 3.6 ng/ml and for the rat kit is 2.5 ng/ml, both of which are very good and should easily accommodate most research needs.
The actual assay procedure is very standard and easy to complete, and the wavelength filter at 450 nm is very common, making the assay very adaptable to virtually any lab that has access to a 96-well plate reader. Because the assay requires multiple washings, the use of an automatic plate washer can reduce the total assay time, but even without the washer an assay can be completed in less than 2 hr. Thus, reliable and accurate results can be obtained in a relatively short period.
We have had great success obtaining accurate and reliable results using their different kits (rat and canine CRP) to satisfy our research purposes and are very comfortable with this product. In addition to the excellent products, Helica Biosystems clearly values its customers as indicated by the excellent technical and customer service. For these reasons, this product and company are highly recommended.
C-Reactive Protein ELISA Kits From Helica Biosystems, Inc.
Simple assay procedure; kits contain all required reagents (including the buffers) for plasma/serum measurements; highly reliable results.
The standard curve can be improved by amending the protocol slightly to consist of a serial dilution starting with the highest standard and the calculation of results can be confusing if you are not familiar with the dilution of samples.
The Bottom Line
Helica provides a quick, simple and reliable assay for the measurement of CRP from a variety of mammalian species.