Immunodiagnosis of invasive pulmonary aspergillosis in rabbits. Fungal antigen detected by radioimmunoassay in bronchoalveolar lavage fluid.

To improve antemortem diagnosis of invasive pulmonary aspergillosis, we used a radioimmunoassay to detect an Aspergillus fumigatus antigen in bronchoalveolar lavage fluid (BALF) and evaluated this technique in a model of disseminated aspergillosis. Antigen was detected in 91% of BALF samples obtained from 11 rabbits with major pulmonary aspergillosis. In an additional 10 rabbits with only minor pulmonary involvement, antigen was detected in 40% of concentrated lavage samples. In contrast, antigenlike activity was found in only 1 of 17 BALF samples from control animals with systemic candidiasis, in none of 9 control animals with staphylococcal pneumonia and in none of 10 normal control animals. Although antigen was present in the serum of 76% of animals infected with Aspergillus, 27% of those with major pulmonary involvement had antigen detected in BALF alone. We found that an extracellular microbial antigen can be detected in BALF and that this technique in the disseminated aspergillosis model is both sensitive and specific for invasive pulmonary disease.