Enzyme-linked immunosorbent assay (ELISA) for IgG antibodies in farmers' lung disease

The ELISA was used for detection of specific IgG antibodies to Micropolyspora faeni antigens in 158 farmers with a history of exposure to mouldy hay, eighty-eight of whom had a diagnosis of farmers' lung. The farmers’ lung group had significantly higher values in the ELISA than both the seventy exposed but asymptomatic farmers (P < 0.001) and a group of thirty-one adult controls (P < 0.001). The asymptomatic farmers also had significantly higher values than the control group (P < 0.02). The ELISA correlated better with the clinical diagnosis than the Ouchterlony agar-gel double-diffusion (precipitin) test. None of the control group gave positive reactions in the ELISA or the precipitin tests. The ELISA is therefore a sensitive, specific and quantitative test which is readily available and widely applicable.