125I labelling of C-reactive protein for the development of Radioimmunoassay (RIA)

Radioimmunoassay (RIA) for C-reactive protein (CRP) is a clinical tool to quantify CRP, a cardiovascular diseases (CVDs) marker, in human serum. Development of the Radioimmunoassay includes radioiodination of CRP with 125 I radioisotope, where radioiodination is conducted following the Chloramine-T method. The present study standardizes the radiolabeling procedure and key reagent concentrations like chloramine-T (oxidizing reagent), sodium metabisulfite, and potassium iodide. The outcome of the standardized radioiodination includes a reaction time of 60 s, iodination analytical parameters like % Radiochemical purity was ~ 97% with specific activity ~ 17 µCi/µg, and the tracer was stable for the 60 days. The optimized radioiodination method is simple, reproducible, and has high tracer stability with high immunoreactivity to develop an RIA procedure to quantify CRP in human serum.