Characterization of bronchoalveolar lavage T cell subsets in sarcoidosis on the basis of CD57, CD4 and CD8

T cells expressing CD57 (a natural killer cell marker) with interferon-gamma (IFN-gamma) producing capacity increase under various conditions. CD57(+) T cells are also present in the bronchoalveolar lavage fluid (BALF) of sarcoidosis, and several phenotypical and functional analyses of these cells have been reported. In the present study, BALF T cells obtained from 52 patients with sarcoidosis were classified further into CD4(+)CD57(+) T cells, CD4(+)CD57(-) T cells, CD8(+)CD57(+) T cells and CD8(+)CD57(-) T cells and their phenotypes and functional characteristics were assessed. Substantial proportions of these T cell subsets expressed natural killer cell markers CD161 and CD122. The biased expansion of Vbeta2 T cells was observed in both CD4(+)CD57(+) T cells and CD4(+)CD57(-)T cells in BALF from most patients, while the expansion of other Vbeta T cells was also observed in some patients. Unexpectedly, the biased expansion of certain Vbeta T cells was also seen in either CD8(+)CD57(-) T cells or CD8(+)CD57(-) T cells, while the expanded Vbeta T cells in CD8(+) T cells differed substantially among individuals. BALF T cells showed a remarkably lower T cell receptor (TCR) intensity than that of peripheral blood T cells. Both CD8(+) T cell subsets in BALF of sarcoidosis expressed the intracellular perforin/granzyme B, while all four subsets expressed intracellular IFN-gamma after in vitro activation, and CD4(+) T cells, especially CD4(+)CD57(-) T cells, expressed tumour necrosis factor-alpha. These findings indicate that CD57(+) T cells as well as CD57(-) T cells in the BALF are phenotypically and functionally different from peripheral blood T cells and may play an important role in the Th1 dominant state and inflammation in pulmonary sarcoidosis.