Immunological determination of free human protein S and C4bp-protein S complex

摘要

A method of immunologically determining free human protein S in an assay sample, which comprises contacting a primary antibody fixed to an insoluble solid carrier and a labelled secondary antibody with the assay sample, the primary and secondary antibodies having the property of binding to different epitopes of free human protein S, and one of the primary and secondary antibodies being a monoclonal antibody having the property of not binding to a complex of the human protein S and human complement cofactor C4b-binding protein (C4bp) but specifically binding to the free human protein S. Also provided is a method of immunologically determining a complex of human protein S and human complement cofactor C4b-binding protein (C4bp) in an assay sample, which comprises contacting a primary antibody fixed to an insoluble solid carrier and a labelled secondary antibody with the assay sample, one of the primary and secondary antibodies being a monoclonal antibody having the property of not binding to free human protein S and human complement cofactor C4b-binding protein (C4bp) but binding specifically to the complex, and the other being an antibody having the property of binding to the human complement cofactor C4b-binding protein (4Cbp).