Polarized type 1 cytokine profile in bronchoalveolar lavage T cells of patients with hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is characterized by an inflammatory lymph ocytic alveolitis comprised of both CD8(+) and CD4(+) T cells, Animal model s suggest that HP is facilitated by overproduction of IFN-gamma, and that I L-10 ameliorates severity of the disease, indicating a Th1-type response. T o determine whether a Th1 phenotype in HP also exists clinically, bronchoal veolar lavage (BAL) and peripheral blood (PB) T cells were obtained from HP individuals and analyzed for Th1 vs Th2 cytokine profiles. It was determin ed that soluble OKT3-stimulated BAL T cells cocultured with alveolar macrop hages produced more IFN-gamma and less IL-10 than PB T cells cocultured wit h monocytes, but no difference was observed in IL-4 production. The monocyt ic cells did not account for this difference, as CD80 and CD86 expressions were similar, and coculturing PB T cells with alveolar macrophages resulted in no difference in IFN-gamma production, Similarly, there was no differen ce in IL-12 production between stimulated BAL or PB T Cells; however, addit ion of rIL-12 significantly increased production of IFN-gamma by BAL T cell s, but not by FB T cells. This effect was due to a difference in IL-12R exp ression, High affinity IL-12R mere only present in association with BAL T c ells, These studies indicate that clinical HP is characterized by a predomi nance of IFN-gamma-producing T cells, perhaps resulting from a reduction in IL-10 production and an increase in high affinity IL-12R compared with blo od T cells.