Galactoxylomannan Does Not Exhibit Cross-Reactivity in the PlateliaAspergillusEnzyme Immunoassay

Abstract

Given the recent report of a false-positive result in the Platelia Aspergillus enzyme immunoassay in a patient with cryptococcosis and in yeast extracts and purified galactoxylomannan of Cryptococcus neoformans, we evaluated culture extracts, purified polysaccharides, clinical specimens, and specimens from animals following experimental infection. Our results revealed no cross-reactions.

Cross-Reactivity of Paracoccidioides brasiliensis , Histoplasma capsulatum , and Cryptococcus Species in the Commercial Platelia Aspergillus Enzyme Immunoassay

“…The C. neoformans cell wall contains galactoxylomannan, an antigen similar to galactomannan, which may result in a cross-reaction in the galactomannan test (2). However, this was not confirmed in a recent study (3). The hypothesis that genotypic variations could explain the differences observed among studies with C. neoformans remains to be tested.…”

Detection of Circulating Galactomannan in Serum Samples for Diagnosis ofPenicillium marneffeiInfection and Cryptococcosis among Patients Infected with Human Immunodeficiency Virus

“…Alternatively, this finding may be caused by C. neoformans galactoxylomannan, which cross-reacts with the Aspergillus GM antigen assay (4). However, the cross-reactivity was not confirmed in a recent comprehensive study (5). Since determination of serum cryptococcal antigen levels using a latex agglutination test is sensitive and specific for immunocompromised hosts, it will not hamper the usefulness of the GM antigen assay in the diagnosis of invasive fungal infections in HIV-infected patients.…”

Galactoxylomannans from Cryptococcus neoformans Varieties neoformans and grubii Are Structurally and Antigenically Variable

“…Given this structural variability, it is possible that GalXM made in vivo is structurally different from that made in culture. In fact, it is conceivable that interstrain and growthrelated differences in GalXM structure are responsible for discrepant results observed regarding serological cross-reactivity of the polysaccharide with other antigens (7,8). Given that GalXM has now been associated with profound immunological derangements (26,27,30), it is likely that this polysaccharide makes a contribution to the virulence composition of C. neoformans (9,20,23).…”