Evaluation of a test to detect circulatingAspergillus fumigatusantigen in a survey of immunocompromised patients with proven or suspected invasive disease

Abstract

An ELISA for the detection and measurement ofAspergillus antigenaemia has been developed and evaluated by examining sera submitted over a 12-month period from immunocompromised patients with a likelihood of invasive aspergillosis. Results from proven cases ofinvasive aspergillosis confirmed at post-mortem and specimens from individuals with suspected disease showed that tests on single serum samples were often negative. Multiple specimens from the same patient greatly increased the frequency of deteclion. Repeated monitoring of sera from a single patient showed wide fluctuations in antigen level, which was considered to be due partly to the medical regimen to which the patient was subject. Control sera from healthy laboratory personnel were consistently negative, but a number of 'at-risk' patients without other evidence of invasive aspergillosis sometimes had low amounts of antigen.Concentrations of Aspergillus antigen of 100 ng ml-~ or higher were considered to be strongly suggestive of fungal invasion.Patients whose host defense mechanisms have been compromised by immunosuppressive drug therapy are particularly susceptible to invasive fungal infection. In such cases cultural methods of detection and serological tests for antibody are often unsatisfactory.Enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA) and agglutination procedures have been reported which detect antigenaemia in patients with candidosis [25,19,2,8] and coccidioidomycosis [22]. Detector antigens that have been used with success in inhibition systems include Candida cell wall mannan [25,19] and cytoplasmic antigen from Candida yeast phase cells. Similar tests have been evaluated as diagnostic aids for aspergillosis. The antigens used as sensitizing agents for detector plates in ELISA inhibition tests include predominantly carbohydrate entities [18], glycoprotein fractions [14] and purified galactomannan [7]. Some of these antigens have also been used in RIA procedures, namely purified galactomannan [7]

Comparison of an enzyme immunoassay and a latex agglutination system for the diagnosis of invasive aspergillosis in bone marrow transplant recipients

“…Since the first report by Reiss and Lehmann, 12 several methods have been used to detect Aspergillus antigens in biological specimens (sera and urine) of patients with invasive aspergillosis. [13][14][15][16][17][18][19][20][21] Among all Aspergillus cellular products, galactomannan has been studied the most extensively and it has been shown to be …”

Immunodiagnosis of aspergillosis

“…Studies with purified antigens would be of value in understanding both humoral and cell-mediated arms of immune response in aspergillosis. In contrast, the lymphokines and the cellmediated mechanisms by which T cells participate in the regulation of IgE synthesis and eosinophil activation and differentiation in certain other allergic diseases have been well documented (99,231 (6,124,190 (80,82,115,132,172,194,197,249 (74,115,122,197,248,250). On the other hand, in IA, galactomannan and glycoproteins are the major circulating antigens (25,50,179 (101,114,228,229).…”

“…When the 250,000-molecular-weight antigen was used in ELISA to test the sera from patients with aspergilloma, 13 Immunoblotting. Several studies have shown that glycoprotein antigens, a major constituent of both the mycelium and the culture filtrate of A. fumigatus, have high immunological reactivity (23,74,115,197,246,250). These antigens can be characterized by their molecular size, isoelectric points, ability to bind to ConA or other lectins, and enzymatic activity.…”

“…Weiner and associates used competitive binding RIA for detecting cell wall carbohydrates and found antigenemia in 78% of the patients with aspergillosis and leukemia (244). Other investigators used inhibition ELISA to quantitate specific antigens in the sera of patients with aspergillosis and of those predisposed to aspergillosis (50,56,183,186,250 (56). Our study, in which we used a double-sandwich inhibition BALISA, dem-onstrated the presence of heat-stable A. fumigatus antigens in sera from all five bone marrow recipients with aspergillosis (91).…”

“…A number of investigators have evaluated methods for detecting A. fumigatus antigens in the bronchoalveolar lavage fluid, sera, and urine of patients with aspergillosis (9,50,58,78,91,186,205,244,245,250,255). The recent reports on the detection of antigenemia are summarized in Table 3.…”