Abstract: Objective To reveal the potential risk of the negative samples near the critical value in detection of human immunodeficiency virus antibody by chemiluminescence immunoassay. Method The samples were selected by chemiluminescence immunoassay（CLIA） for antibodies against HIV in which absorbance of the sample's cutoff value（S/CO）between 0.3 and 0.9,and checked by enzyme linked immunosorbent assay（ELISA）. Result One hundred and thirty-four samples over 0.3<S/CO<0.9 were screened from 64425 clinical samples by CLIA. Among them,2 cases were positive withr ELISA. The two positive cases,however,turned to be negative four weeks later. Conclusion Detection of CLIA HIV antibodies based on the threshold of 0.3<S/CO<0.9 will be able to ensure the safety in HIV diagnosis.

Key words: Chemiluminescence immunoassay, Enzyme linked immunosorbent assay, HIV antibody, Western blot