A sensitive and wide-scale enzyme-immunoassay for human transferrin.

We describe an ELISA technique for human transferrin. The test has a lowest detection limit of 2 micrograms/l and a wide range. It is specific for human transferrin and its reproducibility proved acceptable in both intra-run and between-day examinations. Results obtained by radial immunodiffusion and by ELISA were strongly correlated (n = 51; y = 0.92x + 16.1; r = 0.90). The cost in Israel for disposables and chemicals for triplicate examination is $0.55 per sample. This is 7-8 times less than the cost of a determination, using commercial immunodiffusion plates. This assay is of particular value where the sample size is limited, e.g. samples of 1-4 microliters are sufficient for the determination of transferrin in tears. The transferrin concentrations in arterial and venous cord blood were shown to be essentially identical and similar to that in adult blood.