[Exogenous allergic alveolitis: assessment of antigen-specific IgG antibodies using a new chemiluminescence method]

The demonstration of elevated levels of antigen-specific IgG antibodies is of importance for the diagnostic workup of patients with a suspected hypersensitivity pneumonitis. We established a solid phase immunoassay for the determination of these antibodies based on chemiluminescence (CLIA). The CLIA demonstrated a low level of unspecific binding. The reproducibility of the CLIA was evaluated by calculating the intra- and inter-variation; the variation coefficient was 4% (intra-variation) resp. 13% (inter-variation). Using the CLIA we quantified IgG antibodies against Aspergillus fumigatus (A.f.), Micropolyspora faeni (M.f.) and Thermoactinomyces vulgaris (T. v.) in the sera of patients with farmer's lung (FL, n = 10), healthy farmers (n = 13) and normal volunteers without prior hay contact (n = 12). For all 3 antigens the antibody levels of patients with FL were significantly higher than the titers of the other groups. As a comparison all sera were tested with an established solid phase radioimmunoassay (RIA). Using the RIA a statistically significant difference could only be demonstrated between the antibody levels of patients with FL and of normal volunteers without prior hay contact and was limited to the antigens A.f. and M.f. Comparing the results achieved with both assays on a point by point basis there was a good correlation for the antigens A.f. (r = 0.69; p less than 0.0001) and M.f. (r = 0.74; p less than 0.0001), whereas the correlation for T.v. was not satisfying (r = 0.42, p less than 0.02). In summary the CLIA is a promising new method for the determination of antigen specific IgG antibodies with the advantages of a radioimmunoassay without its potential hazards.