Abstract: Objective Evaculate the effect of ABS on the test performance of the sandwich enzyme immunoassay of double antibodies kit (ELISA) for ECP . Methods 1. Biotinylation of monoclonal antibody against ECP. 2. The development of double antibodies ELISA kit for ECP. 3. The development of ELISA kit with biotin firstly coated. 4. The development of ELISA kit with avidin firstly coated. 5.The comparison of three methods. Result 1. The comparison of three methods:(1) The linear range、sensitivity and relative deviation of direct coating was 2.5~200 ng/ml, 2.75ng/ml ,11.5％，respectively. (2)Three factors of biotin-avidin coating test were 2.5~500 ng/ml、2.61ng/ml and 10.9％ ,respectively.(3) Three factors of avidin coating test was 2.5~500 ng/ml、2.68ng/ml and 11.9％ , respectively. 2.There was no significant difference among their reproducibility. Avidin coating test was the stablest method and antibody coating test was the simplest method, but its antibody dosage was the highest. Conclusion Biotin-avidin coating can elevate the linear range and sensitivity of the test and it could save antibody dosage and antibody coating time.

Key words: Key wordeosinophilia cationic protein, enzyme linked immunosorbent assay, biotin, avidin