Antibody detection in patients with invasive aspergillosis

: The clinical significance of Aspergillus antibody assays for the diagnosis of invasive aspergillosis (IA) is unclear. In two studies, three different antibody assays were evaluated with patients suffering from proven IA: (i) a commercial haemagglutination test (HAT), (ii) a commercial enzyme immunoassay (EIA) for IgG, IgM, and IgA, and (iii) an experimental mitogillin enzyme immunoassay for IgG, IgM, and IgA. In the first study, 99 serum samples from 26 patients with IA and 22 serum samples from 22 control patients were tested with all the three tests. Ten of the 26 patients (38%) reacted positively in at least one antibody assay. The highest sensitivity was generated by the detection of IgG using the EIA formats (22 and 21%, respectively), the HAT had a sensitivity of 8%. IgM type antibodies were detected in only two patients; no IgA type antibodies were detected. The specificities of the IgG EIA and the HAT were 72 and 85%, respectively. Antibody detection was the single positive laboratory test in two patients with proven and probable IA. In the second study, antibody test results of 60 patients with proven IA were retrospectively evaluated. Fourteen patients (23%) tested positive in the EIA and/or in the HAT. Investigations of the antibody levels in individual immunocompromised patients over time revealed that IgG production started after a mean of 10.8 days after diagnosis of IA. To conclude, antibodies against Aspergillus were detected in 23% of patients with IA. The antibody production started in successfully treated immunosuppressed patients after a mean of 10.8 days after the onset of infection. In particular, the detection of IgG-antibodies with an EIA can be useful for the confirmation of the diagnosis of IA and for the monitoring of the treatment of IA.