CELL-SURFACE EXPRESSION OF 2 MAJOR YEAST ALLERGENS IN THE PITYROSPORUM GENUS

Background We have previously identified two major allergens of Pityro sporum orbiculare and characterized these as 37 kDa and 67 kDa protein s. Objective In the present study we have investigated the presence an d subcellular location of the 37 kDa and 67 kDa allergen components in various members of the genus Pityrosporum as well as in Candida albic ans, Candida parapsilosis and Saccharomyces cerevisiae. Methods To det ect both cell surface and intracellular expression of the allergens, f low cytometry and confocal laser scanning microscopy (CLSM) were used. The cells were stained with indirect immunofluorescent (IIF) or alkal ine phosphatase anti-alkaline phosphatase (APAAP) methods using mouse monoclonal antibodies (MoAbs). Results Ninety-five per cent of the P. orbiculare (P. ovale) cells cultured for 4 days showed cell surface-bi nding of the anti-37 kDa MoAb and 88% of the cells bound the anti-67 k Da MoAb when analysed with IIF and flow cytometry. It was found that t he members of the genus Pityrosporum (Malassezia), P. pachydermatis an d M. sympodialis, expressed the 37 kDa and 67 kDa allergens to a simil ar extent as did P. orbiculare. Less than 5% of the cells of the genus Candida and S. cerevisiae showed positive staining with the MoAbs. Th e CLSM revealed that the 37 kDa and the 67 kDa components were located to the cell wall and could not be detected inside the acetone fixed a nd APAAP stained yeast cells of the genus Pityrosporum. When the yeast cells were cultured for more than 4 days the expression of both aller gens decreased significantly. Conclusion All three members of the genu s Pityrosporum express the 37 kDa and 67 kDa major allergens on the ce ll surface, whereas these proteins could virtually not be detected in the Candida genus and S. cerevisiae.