Shared Amino Acid Motifs in T-cell Receptor β Junctional Regions of Bronchoalveolar T Cells in Patients with Pulmonary Sarcoidosis

摘要

To clarify the nature of the accumulated lung T cells of pulmonary sarcoidosis, we studied bronchoal-veolar and peripheral blood (PB) lymphocytes from Japanese patients for expressed T-cell receptor β-chain variable (TCR Vβ) gene usage. Quantitative polymerase chain reaction technique revealed that the Vβ repertoires of bronchoalveolar and PBT cells were heterogeneous. However, the bronchoalveolar lymphocytes from five out of 10 patients showed overrepresentation of T cells, with a few TCR V? families, which varied among individuals, possibly reflecting a difference in the human leukocyte antigen (HLA) backgrounds. Nucleotide sequence analysis of third complementarity determining region (CDR3) segments in overrepresented Vβ families demonstrated limited diversity of the transcripts. Two HLA-DR 12(5)~+ individuals with overrepresented Vβ6 gene transcripts in the lungs shared a common amino acid motif within their CDR3. By contrast, non-overrepresented TCR Vβ transcripts did not show clonal expansion, and the oligoclonal clones in the lung were not found in PB of the corresponding patient. These results showed that, at least in subsets of Japanese patients with pulmonary sarcoidosis, a limited number of T-cell clones are accumlated in the lung in response to a specific antigen. They may mediate an immune response to shape pathology of the disease.