Identification of antigens in BAL fluid in Sarcoidosis

Activated T lymphocytes of the Th-1 type are typically accumulated in the lungs of patients with sarcoidosis, and there they may recognize specific sarcoidosis antigens, presented by antigen presenting cells such as dendritic cells and/or alveolar macrophages. In line with this, previous studies have indicated alveolar macrophages to contain proteins that could induce granuloma formation. Also, signs of a specific immune response in the lungs of HLA-DRB1*0301 positive sarcoidosis patients suggest the presentation of specific antigens by HLA class IImolecules on BAL cells. A number of peptides have therefore been eluted from HLA-DR molecules of BAL cells of HLA-DRB1*0301 positive sarcoidosis patients and these peptides are now used in stimulation tests to analyse their capacity to elicit T cell responses, using an elispot assay. Interestingly, all peptides identified so far were derived from self proteins, indicating autoimmune reactions in the lungs of these patients. These studies may lead to the identification of (a) sarcoidosis specific antigen(s).