IA-LIKE ANTIGENS ON T-CELLS AND THEIR SUBPOPULATIONS IN PULMONARY SARCOIDOSIS AND IN HYPERSENSITIVITY PNEUMONITIS - ANALYSIS OF BRONCHOALVEOLAR AND BLOOD-LYMPHOCYTES

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Abstract
The expression of Ia antigens on T cells from lung and blood was studied as a sign of T cell activation in 17 patients with active pulmonary sarcoidosis, in 12 patients with inactive sarcoidosis, in 9 patients with hypersensitivity pneumonitis, and in 10 normal control subjects. Lymphocyte subsets were identified by mouse monoclonal-antibodies using a peroxidase-antiperoxidase method. Patients with active sarcoidosis and patients with hypersensitivity pneumonitis had a significant increase in Ia+ T cells in bronchoalveolar lavage fluid compared with that in patients with inactive sarcoidosis and that in control subjects (P < 0.01). Blood T cells from the same patients did not show this sign of activation. The highest numbers of Ia+ T cells were recovered from the lungs of patients with hypersensitivity pneumonitis, indicating the high state of activation of immunoregulatory T cells in this disease. Additional analysis revealed that in sarcoidosis, Ia+ lung T cells were exclusively of the OKT4+ helper phenotype, whereas in hypersensitivity pneumonitis, OKT4+ helper as well as OKT8+ suppressor lung cells expressed in part Ia antigens. Different T cell subpopulations are activated in sarcoidosis and in hypersensitivity pneumonitis.