Semi-quantitative adsorption for detection of antibodies to Candida albicans germ tubes by indirect immunofluorescence test.

Adsorption of antibodies against antigens expressed on the Candida albicans blastoconidia cell walls was standardized for the detection of antibodies to germ tubes by an indirect immunofluorescence test (IIFT). Sera from rabbits immunized with C. albicans bearing germ tubes, were diluted by two-fold serial dilutions to obtain specimens 1 : 640-1 : 20 positive by IIFT. Different volumes of specimens were adsorbed with different amounts of whole, heat-inactivated C. albicans blastoconidia. It was found that a 1 : 640 titre serum should be adsorbed at 30 microl by 50 mg cells, down to a 1 : 20 titre serum at 110 microl by 12.5 mg cells. Accurate detection of anti-germ tube antibodies by IIFT depends on the semi-quantitative relation between the positive titre of the specimen and the amount of blastoconidia used in adsorption.