Farmer's lung: Patients’ IgG 2 antibodies specifically recognize Saccharopolyspora rectivirgula proteins and carbohydrate structures

• Published in: Journal of allergy and clinical immunology Vol. 98; no. 2; pp. 441 - 450
• Main Authors: Mundt, Cornelia, Becker, Wolf-Meinhard, Schlaak, Max
• Format: Journal Article
• Language: English
• Published: Mosby, Inc 1996
• Subjects: carbohydrate antigens; concanavalin A; extrinsic allergic alveolitis; Farmer’s lung; IgG 2; protein antigens; Saccharopolyspora rectivirgula (Micropolyspora faeni); concanavalin A; MW; IEF; IgG 2; WGA; SDS-PAGE; Saccharopolyspora rectivirgula (Micropolyspora faeni); Farmer’s lung; pI; extrinsic allergic alveolitis; protein antigens; pK; carbohydrate antigens; ACA; ConA; TFMS
• ISSN: 0091-6749
• DOI: 10.1016/S0091-6749(96)70169-0

Farmer’s lung is a frequent form of extrinsic allergic alveolitis. In Europe and Northern America the main source of the antigenic components that induce farmer’s lung is the bacterium Saccharopolyspora rectivirgula (Micropolyspora faeni). It remains unclear, however, which S. rectivirgula components are responsible for the disease. We approached these problems by investigating the serologic reaction of patients with farmer’s lung and demonstrated specific binding of patients’ IgG 2 to S. rectivirgula antigens. No such antibodies were found in exposed, unaffected subjects. Thus IgG 2 antibodies reacting with S. rectivirgula antigens are useful for the serologic diagnosis of patients with farmer’s lung and for the isolation of disease-causing antigens. After separation of S. rectivirgula extract on concanavalin A–Sepharose (Pharmacia, Uppsala, Sweden), we found that approximately one third of the patients’ IgG 2 reactivity occurred with nonglycosylated proteins. Among these, we characterized two major acidic proteins with molecular weights of 12 and 30 kd, respectively, and with identical N-terminal sequences. Approximately two thirds of the patients’ IgG 2 reactivity was observed against concanavalin A–binding glycoproteins that contained mainly glucose, mannose, and galactose residues. Deglycosylation of the concanavalin A–bound fraction indicated that most of the IgG 2 reactivity occurred with the carbohydrate components. (J A LLERGY C LIN I MMUNOL 1996;98:441-50.)