Abstract: ABSTRACT: Objective To prepare human rBPI23 and acquire its specific polyclonal antibody by immunizing rabbits, so that lay the foundation for preparation of its monoclonal antibody and later setting up immunological testing method for BPI. Methods PBV220-synBPI600 expressing vectors were transferred into competent cell, and the recombinant protein was expressed as inclusion body by temperature control. Its molecular weight was certified by SDS-PAGE, and antigenic specificity was analyzed by Western-blot. Antiserum against rBPI23 was acquired by immunizing rabbits, and the polyclonal antibody was purified by saturated ammonium sulphate precipitation. The titer of antibody was tested by indirect ELISA , and the specificity of antibody was analyzed by Western-blot. Results The recombinant protein was expressed mainly as inclusion body in Ecoli DH5α, SDS-PAGE showed that its molecular weight is 23 kD, which is consistent with the previous theoretical expection. The recombinant protein was analyzed by western-blot with rabbit polyclonal antibody against human BPI, and found that it could be recognized specifically by this polyclonal antibody. High titer of polyclonal antibody（1:320000） was acquired by immunizing rabbits, western-blot analysis revealed that these polyclonal antibodies could specifically react with rBPI23 and human standard sample of BPI. Conclusion Human rBPI23 was successfully prepared, and high titer of polyclonal antibody against human rBPI23 was acquired by immunizing rabbits.

Key words: rBPI23, prokaryotic expression, polyclonal antibody preparation