An indirect immunofluorescence study of antibodies toAspergillus fumigatusin sera from children and adults without aspergillosis

Publisher Website
Google Scholar
Abstract
An indirect immunofluorescence (IF) method for detection of antibodies to Aspergillus fumigatus was developed: it used cryosections of formaldehyde-treated mycelium as antigen. Mycelial age was found to be of importance for titer determination, and growth in Czapek-Dox broth for 48 h at 37°C was considered optimal. Fluorescein-conjugated rabbit antisera to human immunoglobulins reacted by direct IF with A. fumigatus but this staining could be abolished by absorption of conjugates with homogenized mycelium of A. fumigatus. Chessboard titrations revealed plateau end-points of conjugates in the range 0·05–0·2 antibody units ml−1, which is the same range as found in other systems. Sera from 54 adults and 69 children not suspected of having fungal disease were investigated for antibodies to A. fumigatus. IgG antibodies were present at birth and the prevalence and titers fell during the first half year. Through childhood the prevalence and titers of IgG and IgM as well as IgA antibodies increased towards adult levels. In adults IgG antibodies in titers of 40 to 5120 were present in all 54 subjects tested, IgM antibodies in titers 10 to 160 occurred in 91% and IgA antibodies in titers of 10 to 80 in 78%. These findings may be explained by continuous exposure through childhood and adult life to antigens of A. fumigatus or to cross-reacting antigens.