Immunoreactivity of cryptococcal antigen is not stable under prolonged incubations in human serum.
The stability of cryptococcal antigen from Cryptococcus neoformans serotype A and D strains at different temperatures in serum and other solvents was studied. Samples stored at -20 or 4 degrees C had equivalent stabilities as measured by the Premier Cryptococcal Antigen kit and the Cryptococcal Antigen Latex Agglutination System (CALAS) kit. However, using the Premier Cryptococcal Antigen kit, there was a 91% loss of reactivity in samples incubated in human serum for 4 weeks at 37 degrees C. A loss of reactivity of more than 99% was observed after incubation at 45 degrees C for 4 weeks. The capsular antigen was not detected by the Premier Cryptococcal Antigen kit after 16 weeks at elevated temperatures. Antigen titers were also reduced in a latex agglutination assay (CALAS) after 4 weeks at 37 and 45 degrees C. The loss of antigen reactivity was a function of pH and temperature.
McFadden
Diane C
DC
Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Ave., Golding 701, Bronx, NY 10461, USA.
Zaragoza
Oscar
O
Casadevall
Arturo
A
D000911:Antibodies, Monoclonal / Q000276:immunology; D000946:Antigens, Fungal / Q000032:analysis / Q000097:blood / Q000276:immunology*; D003455:Cryptococcus neoformans / Q000276:immunology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007841:Latex Fixation Tests; D011134:Polysaccharides / Q000032:analysis; D011933:Reagent Kits, Diagnostic; D013696:Temperature
D000911:Antibodies, Monoclonal; D000946:Antigens, Fungal; D011134:Polysaccharides; D011933:Reagent Kits, Diagnostic; C027478:glucuronoxylomannan