Kazuki Harada1, Tsuyoshi Oguma2, Akemi Saito3, Yuma Fukutomi3, Jun Tanaka1, Katsuyoshi Tomomatsu1, Masami Taniguchi3, Koichiro Asano1. 1. Division of Pulmonary Medicine, Department of Medicine, Tokai University School of Medicine, Kanagawa, Japan. 2. Division of Pulmonary Medicine, Department of Medicine, Tokai University School of Medicine, Kanagawa, Japan. Electronic address: tyoguma@tokai-u.jp. 3. Clinical Research Center for Allergy and Rheumatology, Sagamihara National Hospital, Kanagawa, Japan.
Abstract
BACKGROUND: Several serological tests for specific precipitin or IgG are available to demonstrate type III hypersensitivity reactions to Aspergillus species and are essential for infectious fungal disease diagnosis. These assays are also important for allergic bronchopulmonary aspergillosis (ABPA) diagnosis; however, their concordance in ABPA was not well studied. METHODS: Fifty-two ABPA patients diagnosed based on ISHAM criteria were enrolled. Precipitins and IgG specific to Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, or Aspergillus terreus were measured using Ouchterlony double immunodiffusion tests and ImmunoCAP method, respectively. A. fumigatus-specific IgG was also determined using complement-fixation (CF) method. RESULTS: Forty-eight percent of cases were double-positive for A. fumigatus-specific precipitin and IgG (ImmunoCAP), whereas 3 (6%) and 14 (28%) cases were positive for precipitin or IgG alone, respectively. Kappa coefficient between these measurements was 0.32, suggesting poor concordance. Double-positive cases were more likely to present: Aspergillus sp. in sputum culture, lower pulmonary functions, peripheral blood eosinophilia, higher total IgE and A. fumigatus-specific IgG titer than precipitin-negative cases. A. fumigatus-specific IgG (CF) was positive only in 8 (15%) cases. The presence of A. fumigatus-specific precipitin or IgG was associated with antibodies specific for other Aspergillus spp., suggesting cross-reactivity. CONCLUSIONS: Positive rate of A. fumigatus-specific precipitin or IgG (ImmunoCAP) was superior to IgG (CF), but relatively poor concordance was noted between precipitin and IgG (ImmunoCAP). Positive precipitin for A. fumigatus suggests more active diseases. Cross-reactivity may exist between antibodies to different Aspergillus spp. Therefore, the type III hypersensitivity results in ABPA diagnosis should be carefully evaluated.
BACKGROUND: Several serological tests for specific precipitin or IgG are available to demonstrate type III hypersensitivity reactions to Aspergillus species and are essential for infectious fungal disease diagnosis. These assays are also important for allergic bronchopulmonary aspergillosis (ABPA) diagnosis; however, their concordance in ABPA was not well studied. METHODS: Fifty-two ABPA patients diagnosed based on ISHAM criteria were enrolled. Precipitins and IgG specific to Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, or Aspergillus terreus were measured using Ouchterlony double immunodiffusion tests and ImmunoCAP method, respectively. A. fumigatus-specific IgG was also determined using complement-fixation (CF) method. RESULTS: Forty-eight percent of cases were double-positive for A. fumigatus-specific precipitin and IgG (ImmunoCAP), whereas 3 (6%) and 14 (28%) cases were positive for precipitin or IgG alone, respectively. Kappa coefficient between these measurements was 0.32, suggesting poor concordance. Double-positive cases were more likely to present: Aspergillus sp. in sputum culture, lower pulmonary functions, peripheral blood eosinophilia, higher total IgE and A. fumigatus-specific IgG titer than precipitin-negative cases. A. fumigatus-specific IgG (CF) was positive only in 8 (15%) cases. The presence of A. fumigatus-specific precipitin or IgG was associated with antibodies specific for other Aspergillus spp., suggesting cross-reactivity. CONCLUSIONS: Positive rate of A. fumigatus-specific precipitin or IgG (ImmunoCAP) was superior to IgG (CF), but relatively poor concordance was noted between precipitin and IgG (ImmunoCAP). Positive precipitin for A. fumigatus suggests more active diseases. Cross-reactivity may exist between antibodies to different Aspergillus spp. Therefore, the type III hypersensitivity results in ABPA diagnosis should be carefully evaluated.