Justification. Although immunoassay has become a second tier analytical tool, there are select cases where it is superior to other analytic methods. In the measurement of inulin in complex biological extracts, immunoassay offers many advantages. Because dogma suggests that inulin is not immunogenic, an immunoassay for inulin has not been explored. The lack of a widely accepted method to measure glomerular filtration rates (GFR) using inulin, the gold standard GFR probe, in animal models and in clinics has had profoundly negative effects on developing drugs for treating kidney disease, assessing kidney transplant recipients and donors, minimizing nephrotoxicity in drug development, and accurately assessing nephrotoxicity in clinical settings. Results and Applications. We have developed a sensitive, specific, high titer antiserum against inulin, a linear β(2→1) fructose polymer with minimal antigenic structure. Rabbits injected with an albumin-inulin conjugate all had high titer anti-inulin antiserum in 3 months. Anti-inulin antiserum binds linear β(2→1) polyfructans with a degree of polymerization greater than 4 with exquisite specificity, does not bind fructose, glucose or glucose polymers (dextran, starch or glycogen), levan (a linear β(2→6) polyfructan), or other common disaccharides and polysaccharides. As anticipated, our anti-inulin antibody binds sinistrin, a polysaccharide similar to inulin, used in clinical practice in some countries. The sensitivity of our assay is about 5ng inulin/mL. Reproducibility measurements performed in rat or human serum and human urine have CVs of less than 12%. Spike and recovery experiments performed in rat serum gave recoveries between 85% and 112%. The assay protocol uses solid phase and ELISA technology and can be completed in 70 minutes. The sensitivity of our anti-inulin antibody allows inulin doses 10 to 100 times lower than inulin doses used in previously reported GFR protocols. The correlation coefficient between our inulin immunoassay and a fluorescent inulin assay in human serum was 0.98. The pharmacokinetics in rabbit blood of three GFR probes were compared. The three probes, inulin by our immunoassay, inulin-FITC by fluorescence and Gd-DTPA by immunoassay, gave nearly identical results. In addition to assessing kidney function, the high sensitivity of our inulin immunoassay can detect dietary inulin in human urine for applications in nutritional research, food science, and inulin-based drug development.

Inulin is immunogenic as shown by development of an immunoassay for inulin

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.