Detection of polysaccharide antigens of Candida albicans interfering with specific antibodies in human sera

A double antibody sandwich radioimmunoassay was developed for the detection of circulating polysaccharide antigens of Candida albicans. The sensitivity of the assay for polysaccharides was 1 ng/mL. The in-vitro interference of specific polysaccharide antibodies, even from sera with low antibody levels, could be demonstrated. The sensitivity of the antigen detection decreased proportionally to the amount of polysaccharide antibodies in the sera. The sensitivity of the assay was almost completely restored by heating the sera. This procedure destroyed antibodies and the released polysaccharide antigens were detectable in the test system by using radiolabelled anti-polysaccharide antibodies. (author)