Immunochemical studies of a purified antigen from Micropolyspora faeni.

A pure antigen fraction was isolated from the crude culture filtrate of Micropolyspora faeni by gel filtration and affinity chromatography. The isolated antigen has a mol. wt of approximately 16,000 and an isoelectric point of pH 3.8. The major amino acid content of this fraction includes glycine, glutamic acid, aspartic acid and alanine. This antigen fraction reacted with the sera of all 15 farmer's lung patients and 20 asymptomatic farmers with circulating anti-M. faeni antibodies. An ELISA method was developed using the purified antigen to detect specific circulating antibodies against M. faeni in farmer's lung patients.