Immunological parameters in farmers with chronic lung disease.

The serum concentrations of IgG, IgA, IgE, C3 (B1A), C4 and alpha 1 AT were measured in 8 farmers with chronic pneumopathy, who showed precipitins against M. faeni or T. vulgaris in the serum. A group of 8 precipitins negative farmers who had worked in barn and 28 normal subjects served as control. IgG were elevated in the patients with detectable precipitins; levels of serum IgA in patients with precipitating antibody were lower than in the subjects without them. The mean levels of C3 were significantly lower in the farmers with detectable precipitins than in the farmers without precipitating antibody and in the control group.