Restricted T cell receptor BV gene usage in the lungs and muscles of patients with idiopathic inflammatory myopathies

Objective. To investigate T cell receptor (TCR) expression in 3 different compartments that could be involved in patients with myositis: muscle, lung, and peripheral blood. Methods. Nine patients with polymyositis (PM), dermatomyositis, or inclusion body myositis underwent bronchoscopy and bronchoalveolar lavage (BAL) as well as muscle biopsy and blood sampling. A panel of 19 monoclonal antibodies specific for TCR V-beta (BV) and V-alpha (AV) were used to characterize the TCR profile in CD4+ and CD8+ T cell populations in BAL fluid and peripheral blood by flow cytometry. Muscle biopsy tissues were analyzed by immunohistochemistry. Patients were also typed for HLA-DRB1 and DRB3 alleles. Results. A total of 17 T cell expansions were detected in BAL fluid, 6 in the CD4+ T cell population and 11 in the CD8+ T cell population. Four T cell expansions were detected in peripheral blood. A selective TCR V usage was found in muscle. Two PM patients, both of whom had BAL fluid BV3+ T cell expansions in the CD4 population and in whom BV3 was also a prominent TCR V segment in muscle tissue, shared the HLA-DRB1*03 allele. These 2 patients were the only ones who were positive for anti-Jo-1 antibody. Conclusion. We found a restricted accumulation of T lymphocytes expressing selected TCR V-gene segments in the target organ compartments (i.e., lung and muscle). The occurrence of shared TCR gene segment usage in muscle and lungs could suggest common target antigens in these organs.