Studies on local preparation of double antibody radioimmunoassay for determination of alpha fetoprotein as a tumor marker

The preparation of primary reagents of AFP- RIA technique with low cost is considered to be one of the main objective of labelled compounds Dept., Radioisotope production Division, Hot Labs Centre, Atomic Energy Authority, Egypt. The development of a radioimmunoassay system based on local production of basic reagents for the measurement of AFP in human serum is described. The assay followed by 100 μ1 of locally prepared 125I-AFP to 100 μ1 standards and unknown samples. After overnight incubation at 4 degree, separating reagents were added in following sequence 100 μ1 non-immune rabbit serum (1:200) followed by addition of 100μ1 of donkey anti-rabbit serum, (1:20), then 500μ1 of 8 percentage polyethylene glycol (PEG) were added into all assay tubes. The tubes were allowed to stand for 30 minutes at room temperature and then centrifuged for 15 minutes. the tubes were decanted and counted in a gamma counter. The results of the present study showed that the assay is highly sensitive where the detection limit or minimal detectable dose of AFP assay approximately 1.5 I U/ml. The reliability of the present procedure was assessed by examining its reproducibility on pooled human serum samples selected to represent different levels of AFP. The data of intra-assay and intra-assay precision revealed the consistency of the results obtained by the method of the present study. The present technique for determination of serum AFP agreed well with commercially available kits (DPC, double antibody-diagnostic product corporation, los angeles, USA). The technical simplicity of this specific, accurate and reasonably precise method may suggest that the technique should be suited for routine laboratory use