Antibodies of different immunoglobulin classes against antigens causing farmer's lung

A solid phase radioimmunoassay technique was used to demonstrate antibodies of various immunoglobulin classes in sera against farmer's lung antigens. IgG, IgA, and IgM antibody activity in normal patients and in patients with farmer's lung were detected against Micropolyspora faeni. Only the IgG and IgA antibody activity was different in farmers and in control subjects. An asymptomatic subject could not be differentiated from symptomatic farmers by IgG antibody activity. No IgE antibody activity was detected. The radioimmunoassay technique can be used to show antibody activity against carbohydrate antigens and as a method of evaluation of antigens by inhibition analysis. Certain types of hypersensitivity lung disease can be discriminated by in vitro analysis of serum antibody of various immunoglobulin classes. This is apparent for IgE and possibly true for IgM.