AN IMMUNODOMINANT 90-KILODALTON ASPERGILLUS-FUMIGATUS ANTIGEN IS THE SUBUNIT OF A CATALASE

We have identified, purified, and characterized structurally and funct ionally a 90-kDa immunodominant antigen associated with the water-solu ble fraction of Aspergillus fumigatus. This antigen is recognized by 9 0.3% of serum samples from patients with aspergilloma and should be co nsidered either by itself or better in combination with other purified antigens as a candidate for developing a standardized immunoassay for the detection of aspergilloma. p90 is a glycoprotein containing at le ast two N-linked sugar chains of 2 and 5 kDa, respectively, which are not necessary for its reactivity with aspergilloma serum samples. Usin g specific anti-p90 rabbit serum, we have demonstrated that under nati ve conditions, p90 exists in oligomeric form and has associated catala se activity, This activity is resistant to extreme temperatures (>60 d egrees C), reducing agents (40 mM dithiothreitol), high concentrations of denaturing agents such as 8 M urea and 8% sodium dodecyl sulfate, and treatments with ethanol-chloroform-water (5:3:10 [vol/vol]) mixtur es.