Solid phase 125I labelled radioimmunoassay for spermidine

Using 125I labelled monoclonal antibody against spermidine and solid phase antigen spermidine-bovine serum albumin conjugate, the radioimmunoassay for spermidine was developed. The sensitivity of this method was about 8 times higher than that of liquid phase 14C labelled spermidine radioimmunoassay, reaching detection limit of 10 ng/ml (0.5 ng/tube). The working range of standard curve was 0-105 ng/ml. The new method was suitable for spermidine measurements in saliva, stomach fluid, and cerebrospinal fluid. The coefficients of variation (CV) of within and between-assay were 4% and 13%, respectively. Preliminary clinical measurements showed that the spermidine levels in saliva of cancer patients and in cerebrospinal fluid of leukemia patients were significantly elevated