The isolation of antigens associated with farmer's lung.

The isolation and physicochemical characterization of three of the `major' farmer's lung antigens derived from Micropolyspora faeni is recorded. Antigen 1, the major antigen in the C region is a glycopeptide with an average molecular weight of 85,000 and exhibits extreme heat stability being unaffected by 120°C for 7 days. Antigens 2 and 3, the major antigens in the A and B regions respectively are proteins whose molecular weights are 44,000 and 77,000 respectively and are thermolabile with half lives of 25 days and 20 days at 50°C respectively. The extreme thermolability of certain other antigens is described and their absence from mouldy hay known to be associated with cases of farmer's lung and other considerations suggest that the antigenic stimulus in farmer's lung may in part be attributable to the germination and possible limited development of M. faeni spores in the lungs.