Development of a two-site enzyme immunoassay based on monoclonal antibodies to measure airborne exposure to (1→3)-β- d-glucan

Abstract

(1→3)-β- d-glucan is found in cell walls of some fungi, bacteria and plants. It plays a crucial role in bioaerosol-induced inflammatory reactions. To estimate the level of airborne (1→3)-β- d-glucan exposure, a monoclonal antibody-based two-site enzyme immunoassay (mAb-EIA) was developed. The results obtained with the mAb-EIA were compared with the results of a Limulus amoebocyte lysate-based assay for (1→3)-β- d-glucan. Three mAbs produced by mouse immunization with bovine serum albumin-conjugated laminarin were enriched by in vitro production in a modular minifermenter and affinity purified. Two mAbs were selected for the development of a two-site EIA specific for (1→3)-β- d-glucan. Different polysaccharides, fungal and plant seed extracts, and airborne inhalable dust from workplaces (poultry farms, pig stables, grain storage houses, and a laboratory animal facilility) were sampled with portable pumps and measured with both the mAb-EIA and Glucatell ® assay. Using carboxymethylated curdlan as a standard, the mAb-EIA gave a steep dose-response curve for concentrations between 0.36–15 ng/ml. The mAb-EIA was specific for (1→3)-β- d-glucan and was sufficiently sensitive to detect (1→3)-β- d-glucan in airborne dust samples. In comparing the EIA results to the values obtained with the Glucatell ® assay, the correlation was found to be high (coefficient of correlation r 2 = 0.91), and the mean ratio of the values was 1.7. Depending on the dust source, either the Glucatell ® assay or the mAb-EIA gave higher results. The mAb-EIA is sensitive enough to detect (1→3)-β- d-glucan in airborne dust samples collected with portable pumps. Thus, the assay is suited for the investigation of the health effects induced by exposure to this class of biologically active molecules.