[T lymphocytes in sarcoidosis]

IMPORTANCE OF T-LYMPHOCYTES IN SARCOIDOSIS: Sarcoidosis is thought to result from an uncontrolled granulomatous immune response. T-lymphocytes are an essential component of this immune reaction. The recognition of specific antigens through receptors expressed on the cell membrane activates the T-cells, resulting in the expression of effector functions that ultimately control granuloma formation. T-cells participating in sarcoid reactions are readily accessible using bronchoalveolar lavage, and have been intensively studied. SPECIFICITY OF T-CELLS: Several groups have evaluated the diversity of T-cell receptors expressed by T-cells from patients with sarcoidosis. These studies have demonstrated that oligoclonal T-cell populations are present both in the lung and blood of these patients, findings that support the conclusion that antigen-induced immune responses play a role in the pathogenesis of sarcoidosis. The identification of the antigen(s) recognized by these cells remains an important goal, and may help identify etiologic agents. CYTOKINE PRODUCTION: Considerable progress has been made in characterizing the cytokines produced by T-lymphocytes and other cells participating in the granulomatous reaction. The modulation of the activity of these mediators represents a promising approach for the development of more specific therapeutic agents.