Latex slide agglutination test for Aspergillus antibodies

Adsorption and covalent immobilization of human serum albumin (HSA) and gamma globulins (gamma G) onto poly(styrene/acrolein) latexes with pyrene, dansyl, and 2,4-dinitrophenyl labels

The poly(styrene/acrolein) latexes (P(SA)1 and P(SA)2), differing in poly(acrolein) content, were synthesized by the emulsifier-less emulsion-precipitation polymerization of styrene and acrolein. The fraction of poly(acrolein) in the surface layer was 0.35 and 0.50, for the P(SA)1 and P(SA)2 latex, respectively. Latexes were labelled with 2,4-dinitrophenylhydrazine (DNPH), dansylhdrazine (DAH), and 1-aminopyrene (APY). Surface concentration of labels varied from 4.20.10(-7) mol m-2 (for APY label on P(SA)1 latex) to 1.54.10(-6) mol m-2 (for DNPH label on P(SA)2 latex) reflecting the fraction of polyacrolein in the surface layer and bulkiness of the label. The differences between adsorption and covalent immobilization of human serum albumin and gamma globulins onto the P(SA)2 latex and onto its derivatives labelled with the 2,4-dinitrophenyl (DNP), dansyl (DA), and pyrene (PY) groups were small. The observation conforms to the hypothesis that polyacrolein forms domains on the surface of the P(SA) latexes and that after labelling some aldehyde groups are still available for the covalent immobilization of proteins. Labelled and parent latexes were used in the model slide and turbidimetric aggregation tests for the goat anti-HSA. The fluorescent latexes, labelled with APY and DAH, and latexes labelled and with DNPH were found to be suitable for the model tests, similarly as the nonlabelled ones, however, some differences in the sensitivity, depending on the presence and the nature of labels, were noticed. The standard goat anti-HSA serum (Sigma) was detected at maximum dilution equal to 2000 in the slide test, and in the dilution region from 1.8.10(3) to 4.7.10(6) times in the turbidimetric test.

Obtenção e avaliação de antígenos de Aspergillus fumigatus

Antígenos de três amostras de A. fumigatus (354, 356, JIG) e antissoro contra a mistura destes antígenos foram produzidos e avaliados imunoquimicamente. Os antígenos de filtrado de cultura foram obtidos após concentração com acetona conforme adaptação da técnica descrita por Coleman & Kaufman. Em prova de ID obteve-se 100% de positividade com os soros de pacientes com aspergilose estudados. Com relação aos soros heterólogos encontramos reatividade com soro de um paciente com candidíase e com soro de um paciente com histoplasmose; foi encontrado padrão idêntico de resposta quando se utilizou o antígeno de referência. O antissoro foi titulado por ID, CIE e RFC MI contra o antígeno específico apresentando títulos respectivos de 1:32, 1:32 e 1:128, e utilizado para reagir contra o mesmo antígeno por IEF, demonstrando 8 linhas de precipitação, sendo 5 na região anódica e 3 na região catódica. O perfil de bandeamento do antígeno em eletroforese utilizando gel de poliacrilamida (SDS-PAGE) a 12,5% apresentou-se complexo com 26 sub-unidades protéicas, cujos pesos moleculares variaram de 18 a > 100kDa. Quando estes componentes foram eletrotransferidos e reagidos com o antissoro específico ("immunoblotting"), verificou-se imunogenicidade em todas as frações bandeadas.

Immunodiagnosis of aspergillosis

Aspergillus species are ubiquitous fungi and have been implicated as the causative agents of a variety of lung disorders in humans. These disorders include allergic, saprophytic, and systemic manifestations. The allergic disorders mainly affect atopic persons, and invasive or systemic diseases affect immunosuppressed individuals. Immunodiagnosis can help the practitioner diagnose these diseases. Demonstration of circulating antibodies is a useful criterion, but the lack of dependable and standardized antigens is a limiting factor in the diagnosis of most Aspergillus-induced diseases. Despite this limitation, however, immunodiffusion and enzyme-linked immunosorbent assays have been widely used for the detection of antibodies in the sera of patients with aspergillosis. Similarly, crude and semipurified antigens are being used to demonstrate skin hypersensitivity in patients, and several methods have been useful in the detection of antigenemia in patients with invasive aspergillosis. With a growing number of reports on the incidence of aspergillosis and an increase in the number of immunosuppressed individuals in the population, more rapid methods and more reliable reagents for immunodiagnosis are needed. With recent attempts at obtaining reliable reagents for through hybridoma technology and molecular biological techniques, substantial progress toward efficient immunodiagnosis may be achieved.

Detection of Aspergillus fumigatus serum precipitins by counterimmunoelectrophoresis

Detection of serum precipitins to Aspergillus fumigatus by counterimmunoelectrophoresis is compared with the immunodiffusion technique. Eight of nine (89%) sera from patients with proven A. fumigatus infection were positive by both methods. No serum from subjects with other systemic mycoses, bacterial infections, or healthy controls had detectable precipitins. The highest serum precipitin titers were found in sera of patients with the mycetomal and invasive forms of the disease. Detection of A. fumigatus serum precipitins by counterimmunoelectrophoresis compares favourably with immunodiffusion and has the advantage of significantly reducing the time required for results.

Evaluation of a microtiter latex agglutination test for histoplasmosis

Experiments were designed to evaluate a Microtiter latex agglutination (Micro-LA) test, as a serological aid in the diagnosis of histoplasmosis, and to compare this test with the conventional microtiter-complement fixation (CF) test for histoplasmosis. Sera tested were from cases of acute and chronic pulmonary and disseminated histoplasmosis, as well as from individuals not having histoplasmosis. Ninety-seven percent of the cases of acute pulmonary histoplasmosis had positive Micro-LA tests, whereas 91% had positive CF tests. Ninety-six percent of the patients having chronic pulmonary histoplasmosis showed positive Micro-LA tests and 91% had positive CF tests. In contrast, 64% of the cases of disseminated histoplasmosis had positive Micro-LA tests, whereas 82% had positive CF tests. None of these differences was statistically significant. Although there were no significant differences in complement fixing and agglutinating antibody cross-reactivity with Blastomyces antigens, more patients demonstrated CF titers than Micro-LA titers. Sera from patients with acute and chronic histoplasmosis showed higher Micro-LA titers than CF titers, whereas sera from cases of disseminated histoplasmosis showed higher CF titers. Histoplasmin skin testing has less of a boosting effect on agglutinating antibodies than on CF antibodies to histoplasmin. Anticomplementary sera can be used in the Micro-LA test. This test is simple to perform, and results can be obtained in 2 to 4 hr.

Use of the immunodiffusion test in the serodiagnosis of aspergillosis

The diagnostic value of an immunodiffusion (ID) test with standardized precipitinogens derived from five Aspergillus species was determined with sera from 60 proven and 12 suspected cases of aspergillosis. The data demonstrated that the greatest number of aspergillosis cases were detected by the concurrent use of A. fumigatus and A. niger precipitinogens. With these precipitinogens, the ID test permitted the serodiagnosis of aspergillosis in 82% of the 60 proven cases and in 83% of the 12 suspected cases. The presence of one or more precipitins was indicative of aspergilloma, of allergic bronchopulmonary aspergillosis, or of invasive aspergillosis. Precipitins were detected in 93% of the sera from patients with aspergilloma, in 50% of the sera from patients with allergic bronchopulmonary aspergillosis, and in 88% of the sera from patients with invasive aspergillosis. Although the presence of one or two precipitin bands could indicate any form of aspergillosis, the presence of three or four was strong evidence of either aspergilloma or invasive aspergillosis. The ID test was found to be 100% specific in an evaluation of its effectiveness with 65 sera from individuals with other systemic mycotic infections, bacterial or neoplastic diseases, and from apparently normal humans. In diagnosed cases of aspergillosis, the examination of serial serum specimens provided information about the clinical course of the disease. A reduction in the number of precipitin bands and significant titer changes were noted as the patients responded to therapy.