Mediators of hypersensitivity pneumonitis.

Inhalation of Saccharopolyspora rectivirgula (S. rectivirgula) causes farmer's lung disease, a classic example of hypersensitivity pneumonitis (HP). HP is characterized by bronchoalveolar lavage fluid (BALF) neutrophilia (within the first 48 hours after inhalation), followed by BALF lymphocytosis. We utilized a well-described murine model of HP to determine the timing of the appearance of the C-C chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha); the inflammatory cytokines tumor necrosis factor (TNF), interleukin-1alpha (IL-1alpha), and interleukin-6 (IL-6); and the Th1 -differentiating cytokine interleukin-12 (IL-12) in BALF. After a single intratracheal administration of S. rectivirgula, there was remarkable BALF neutrophilia (peak 24 to 48 hours), followed by a BALF lymphocytosis (peak 48 to 72 hours) in both C57Bl/6 and BALB/c mice that was preceded by the appearance of MIP-1alpha in BALF (peak 4 to 6 hours) and MCP-1 (peak at 48 hours). In both strains of mice there was a striking increase of BALF IL-12 (peak 48 to 72 hours). There was also an increase in BALF IL-6, IL-1alpha, and TNF that was greater in the BALB/c mice than in the C57Bl/6 mice. S. rectivirgula induced the secretion of MIP-1alpha, MCP-1, IL-6, IL-1alpha, and IL-12 from the murine macrophage cell line J774A.1; MIP-1alpha, IL-6, IL-1alpha, IL-12, and TNF from C57Bl/6 alveolar macrophages; and IL-1alpha, IL-6, and TNF-but not IL-12-from BALB/c alveolar macrophages. We conclude that chemokines and cytokines induced by intratracheal administration of S. rectivirgula precede BALF neutrophilia and lymphocytosis and may cause differentiation of Th1 cells; we also conclude that pulmonary macrophages represent a potential source of these substances.

Experimental hypersensitivity pneumonitis: influence of Th2 bias.

Cultured murine CD4+ cells from Saccharopolyspora rectivirgula sensitized C3H/HeJ (Th1 bias) donors can adoptively transfer murine experimental hypersensitivity pneumonitis (EHP). We sensitized BALB/c mice (Th2 bias) with S. rectivirgula, obtained spleen and lung associated lymph node (LALN) cells, cultured the cells with specific antigen, and attempted adoptive transfer of EHP. We also treated both C3H/HeJ and BALB/c donor mice with IL4 and anti-IFNgamma before exposure to S. rectivirgula and then cultured cells from both spleen and LALN before attempted transfer of EHP. We found that cultured spleen and lung associated lymph node cells can adoptively transfer EHP in both C3H/HeJ and BALB/c mice as demonstrated by infiltration of the recipient lungs with CD4+ lymphocytes. Treatment of both mouse strains with IL4 and anti-IFNgamma did not change the ability of cultured cells to adoptively transfer EHP. We conclude that EHP induced by S. rectivirgula can occur in animals with either a Th1 or a Th2 bias and is not altered by treatment with IL4 and anti-IFNgamma. This suggests that attributes of the antigen and not genetic background or cytokine environment at the site of initial sensitization determines the results of exposure to S. rectivirgula.

Effect of glucan on murine lungs.

Glucan, a folded high-molecular-weight polysaccharide, has multiple effects in animals when administered intravenously or intraperitoneally, but not when administered by inhalation. The hypotheses tested were whether intratracheal administration of glucan can cause lung damage and whether some of the resulting lung injury is immunologically mediated. There was a dose-response relationship between the amount of intratracheally injected glucan and the extent of pulmonary histologic abnormalities, which consisted of peribronchiolar and intraalveolar infiltration with chronic inflammatory cells. An attempt to adoptively transfer increased susceptibility to glucan induced lung injury was made. Cells cultured with glucan were transferred into naive recipients before intratracheal glucan exposure. The extent of pulmonary inflammation that occurred as a result of intratracheal injection of glucan was not affected by transfer of cultured cells from glucan-treated animals. However, high concentrations of glucan in culture did produce cells with the appearance of lymphoblasts. These data indicate that glucan induces lung injury, but that there is no evidence of cell mediation of pulmonary injury induced by intratracheal exposure to glucan.

Th1 CD4+ cells adoptively transfer experimental hypersensitivity pneumonitis.

Cultured cells from Micropolyspora faeni-sensitized donors can adoptively transfer murine experimental hypersensitivity pneumonitis (EHP). To determine whether the CD4+ cells responsible for transfer have characteristics of Th1 or Th2 cells, we established cell lines from lung-associated lymph nodes of M. faeni-sensitized C3H/HeJ mice by culturing with antigen and either IFN-gamma, IL2, and anti-IL4, or IL4. Cell lines were stimulated regularly with antigen, fresh antigen-presenting cells, and the cytokine/anti-cytokine antibody cocktail. At various times after initiation of culture, cells were injected intravenously into recipients, which were then challenged intratracheally with M. faeni and sacrificed and the extent of pulmonary inflammatory response was determined. IFN-gamma, IL4, and IL10 levels were determined in supernatants of cell cultures stimulated with M. faeni to characterize the cell lines as Th1 (IFN-gamma, but low IL4 and IL10 secretion) or Th2 (IL4 and IL10, but low IFN-gamma secretion). Cell lines were differentiated into either Th1 (IFN-gamma = 310 +/- 45 U/ml, IL4 = 0.10 +/- 0.1 U/ml, IL10 = 1750 +/- 75 pg/ ml, >99% CD4+) cell lines by Day 16 of culture or Th2 cell lines (IFN-gamma = 1.8 +/- 1.0 U/ml, IL4 = 830 +/- 388 U/ml, IL10 = 51,700 +/- 10,900 pg/ml, >96% CD4+) by Day 30. Th1 cell lines were able to adoptively transfer EHP whereas Th2 cell lines were unable to adoptively transfer EHP. The ability to transfer EHP was directly related to the amount of IFN-gamma and inversely to the amount of IL4 secreted by antigen-stimulated cells. We conclude that it is possible to produce CD4+ cell lines with either Th1 or Th2 characteristics from lung-associated lymph nodes of mice exposed to M. faeni and that only Th1 CD4+ cell lines can adoptively transfer EHP.