Different expansions of T lymphocyte subpopulations in the lung and corticosteroid-induced changes in patients with active pulmonary sarcoidosis.

Abstract

Pulmonary sarcoidosis is a disease characterized by increased numbers of T lymphocytes within the alveolar structures and the consequent spontaneous release of a variety of mediators relevant to the pathogenesis of this disorder. This phenomenon is associated with a different expansion of the T cell subpopulations present in the lung. Using monoclonal antibodies specific for T cell subsets with helper functions, we have evaluated the different T lymphocyte subpopulations present in patients with active and inactive pulmonary sarcoidosis. The small fraction of helper T cells recognized by the 5/9 monoclonal antibody appear to be preferentially expanded in the lung of patients with active disease. The functions of the 5/9+ lung T cells in pulmonary sarcoidosis were evaluated by considering the spontaneous release of monocyte chemotactic factor, the help in immunoglobulin production, and the spontaneous production of interleukin-2 by the 5/9+ lung T cells from patients with active disease. These T cell functions appeared to be restricted to the 5/9+ T cell subset. The sensitivity of the 5/9+ lung T cells to corticosteroid treatment in pulmonary sarcoidosis was studied by performing bronchoalveolar lavage in patients with active disease before and after oral prednisone therapy. Evaluation of lymphocyte subsets after 3 months of therapy showed a marked reduction of 5/9+ T cell percentages even though the overall proportion of lavage cells that were T lymphocytes was still elevated. Thus the 5/9 monoclonal antibody may be considered a good marker in gauging the activity of the alveolitis in pulmonary sarcoidosis because it recognizes the T cell subsets responsible for many activities relevant to the pathogenesis of this disorder. In addition, analysis of the proportions of 5/9+ lung T cells may result in a useful means to evaluate the early response to therapy.