concanavalin-a and Farmer-s-Lung

Farmer's lung (FL) is characterized by an intense lymphocytic alveolitis which persists after an acute episode with continuous exposure to the offending antigens. This study aimed to examine the role of interleukin-2 (IL-2) in the development and persistence of this lymphocytic alveolitis. Three groups of dairy farmers were studied: acute FL, ex-FL (past history of FL but no clinical evidence of active disease) and asymptomatic farmers (no lung disease). IL-2 was measured by enzyme immunosorbent assay and T-cell proliferation was evaluated by 3H-thymidine incorporation. Acute and ex-FL patients had more lymphocytes (p<0.01) and higher levels of IL-2 (p<0.05) in their bronchoalveolar lavage (BAL) than asymptomatic farmers. BAL T-lymphocytes from acute and ex-FL patients released considerable amounts of IL-2 after stimulation with concanavalin A and showed dose-dependent proliferative responses to IL-2. IL-2 production was decreased after treatment with prednisone. Acute FL patients, but not ex-FL, had higher levels of soluble CD25 in their serum than asymptomatics (p=0.009). These results suggest that interleukin-2 may play a role in farmer's lung by providing a stimulus not only for the accumulation of lymphocytes but also for their persistence at the site of hypersensitivity reaction, and that the lung is a likely source of this cytokine in vivo.

Topics: Acute Disease; Bronchoalveolar Lavage Fluid; CD4-CD8 Ratio; Cell Count; Concanavalin A; Farmer's Lung; Female; Humans; Interleukin-2; Lymphocyte Activation; Lymphocyte Subsets; Lymphocytes; Male; Pulmonary Alveoli; Receptors, Interleukin-2

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' IgG2 to S. rectivirgula antigens. No such antibodies were found in exposed, unaffected subjects. Thus IgG2 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' IgG2 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' IgG2 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 IgG2 reactivity occurred with the carbohydrate components.

Topics: Amino Acid Sequence; Antibodies, Bacterial; Antibody Specificity; Antigens, Bacterial; Bacterial Proteins; Binding Sites, Antibody; Carbohydrates; Chromatography, Affinity; Concanavalin A; Farmer's Lung; Glycoproteins; Humans; Immunoglobulin G; Molecular Sequence Data; Saccharopolyspora

Twenty-one different biotinylated lectins were used to recognize the carbohydrates of Aspergillus umbrosus, one of the most common microbes that patients with farmer's lung in Finland are exposed to. The glycoprotein fraction of A. umbrosus was bound especially well by Concanavalin A and consisted mainly of carbohydrates mannose and glucose. The carbohydrate fraction of A. umbrosus antigens were isolated from the crude extract of A. umbrosus with Con A-Sepharose affinity chromatography. Serum IgG antibodies to A. umbrosus mannoprotein fraction were determined in 57 patients with farmer's lung, 10 asymptomatic exposed farmers and 10 healthy controls by enzyme linked immunosorbent assay. Candida albicans and Saccharomyces cerevisiae mannan were used as controls. Patients had high levels, whereas asymptomatic exposed farmers showed moderate, and health controls low levels, of IgG antibodies to the A. umbrosus mannan/mannoprotein fraction. There were no significant differences in the mean antibody levels between the patients and controls against C. albicans or S. cerevisiae mannose fraction although in all groups more antibodies were detected against C. albicans than S. cerevisiae.

Topics: Animals; Antigens, Fungal; Aspergillus; Biotin; Chromatography, Affinity; Concanavalin A; Farmer's Lung; Humans; Immunoblotting; Immunoglobulin G; Lectins; Mannans; Rabbits

Most subjects repetitively exposed to agents responsible for hypersensitivity pneumonitis (HP) do not develop persistent or progressive pulmonary inflammation. To determine if immunologic tolerance is associated with resolution of pulmonary abnormalities despite continuing exposure, we examined markers of local immunologic reactivity in a model of HP in rabbits. Rabbits were exposed to Micropolyspora faeni (M. faeni), the agent responsible for farmer's lung disease, with 3 sensitizing and 2, 4, or 8 challenge intratracheal injections. We determined bronchoalveolar macrophage migration inhibition (MMI) induced by M. faeni antigen, mitogen, and antigen-induced lymphocyte proliferation of lymphocytes derived from the lungs and hilar lymph nodes, and the amount of IgG antibody to M. faeni in serum and bronchoalveolar lavage fluid. We found MMI of lavage cells from rabbits exposed to M. faeni. Migration inhibition was dependent on ongoing protein synthesis. Hilar node and pulmonary lymphocytes proliferated upon exposure to M. faeni antigen, and anti-M. faeni antibody was found in serum and lavage fluid from M. faeni-treated rabbits. There were no differences between rabbits challenged 2, 4, and 8 times. We conclude that resolution of pulmonary histologic abnormalities in this model of hypersensitivity pneumonitis is not associated with evidence of immunologic tolerance.

Topics: Animals; Antibodies, Bacterial; Antibody Formation; Antigens, Bacterial; Cell Migration Inhibition; Concanavalin A; Farmer's Lung; Female; Immune Tolerance; Immunoglobulin G; Lymphocyte Activation; Lymphocytes; Macrophages; Male; Micromonosporaceae; Puromycin; Rabbits