Comparative immunochemical analysis of five Thermoactinomyces strains.

The antigen structures in mycelial extracts of 4 strains of Thermoactinomyces vulgaris and 1 strain of Thermoactinomyces candidus were compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining. For immunological characterization, antigens were transferred electrophoretically to nitrocellulose membranes and blotted with T. vulgaris strain-specific antisera and with sera of farmer's lung patients. Cross-reactions between the strains were also studied using immunodiffusion and crossed immunoelectrophoresis. Protein components between 50 and 60 kilodaltons were found to be the most immunogenic. Patient sera showed heterogeneous responses, but all reacted with an antigen at 55 kilodaltons that was also common to all strains studied.

Lymphocyte activation with release of soluble mediators induced by Thermoactinomyces vulgaris in vitro.

Murine spleen lymphocytes stimulated in vitro with a hypersensitivity pneumonitis-associated bacterium, Thermoactinomyces vulgaris, were found to secrete interleukin-2 up to 7 days after mitomycin C blockade. They exerted helper effect in secondary mitogen or antigen-induced lymphocyte proliferation. Cyclosporin A, an inhibitor of interleukin-2 synthesis, caused a complete abrogation of the helper effect, suggesting that the effect was mainly due to interleukin-2. Indomethacin, an inhibitor of prostaglandin synthesis, enhanced the helper effect in some inbred strains of mice, indicating prostaglandin-dependent downregulation. The strain variation in the prostaglandin-induced downregulation was not H-2 linked.

Immunomodulating properties of lymphocytes activated by farmer's lung associated bacterium Thermoactinomyces vulgaris in vitro.

Thermoactinomyces vulgaris, one of the aetiological agents of farmer's lung, was analysed for its ability to activate non-immune spleen lymphocytes from 10- to 14- week-old mice. The lymphocytes were found to exert both enhancing and suppressing signals after activation, depending on the secondary stimulation used. The enhancing effect is due to interleukin-2 secreted mainly by L3T4+ lymphocytes. The suppressive action is associated with Lyt2+ lymphocytes, which are probably activated by prostaglandins or histamine; but the suppression inducer action of L3T4+ lymphocytes may also be important. Genetic regulation, independent of H-2K and D, was also detected between different inbred strains of mice in response to T. vulgaris. The genetic regulation appeared associated with the different responsiveness of Lyt-2 positive lymphocytes between different strains. These results emphasize the importance of nonspecific activation in hypersensitivity disorders induced by microbiol antigens.

Interactions of Thermoactinomyces vulgaris and mouse alveolar macrophages. Loss of mitogenic activity and release of suppressive prostaglandins and interleukin 1.

Interactions of mouse alveolar macrophages from three different inbred strains of mice and Thermoactinomyces vulgaris, a microbe associated with Farmer's lung disease, were studied. Alveolar macrophages were found to abolish the mitogenic activity of T. vulgaris. A prostaglandin synthesis inhibitor indomethacin, could not restore the activity. Alveolar macrophage supernatants generated by T. vulgaris treatment exerted strong suppression in secondary concanavalin A-induced lymphocyte transformation. Indomethacin partly relieved the suppression but a histamine 2 receptor blocker, cimetidine, had no effect. Interleukin 1 activity was practically undetectable by the thymocyte co-stimulation assay unless indomethacin was used. When indomethacin was used, interleukin 1 activity could be detected in all strains of mice tested. Major differences in the abolition of the mitogenic effect, in the suppressive effect, or in the release of interleukin 1 were not detected between inbred strains of mice tested. The results indicate that alveolar macrophages exert suppressive actions in vitro after T. vulgaris treatment but in vivo activities remain to be elucidated.

Pulmonary and immune responses to a Thermoactinomyces vulgaris antigen respiratory sensitization in C57BL/6J mice.

Lung histology and immune responses were followed during a six month period of Thermoactinomyces vulgaris antigen respiratory sensitization of C57BL/6J mice. Histologically, the mice developed a picture resembling the subacute stage of human farmer's lung. At the early phase of the sensitization a T-cell response was seen in vitro, characterized by an increased spleen but no peripheral blood lymphocyte reactivity to T-cell mitogens at the same time as increased reactivity to the sensitizing antigen was detected. An increase in the percentage of T-cells in the lavage cell population was also seen. The sensitization was associated with the appearance of both IgG and IgA antibodies in lavage and in serum of which lavage IgA antibodies were found to follow the course of the sensitization most accurately. The increase in antibody titers was not, however, reflected in lavage cytology or in lymphocyte reactivity. The results suggest that different immunological reactions may be predominant at different stages of farmer's lung.