Long-term persistence of clonally expanded T cells in patients with polymyositis.

Polymyositis is a CD8(+) T-cell-mediated disease. T-cell clonal expansions are observed at disease onset, but little is known about their persistence over time. Qualitative and quantitative spectratyping demonstrated that PM relapse features dramatically perturbed blood T-cell repertoires but is not associated with the emergence of new T-cell clones. It is striking that patients in remission also maintained all their T-cell repertoire abnormalities. The clonally expanded T-cells displayed a memory phenotype, expressed intracellular perforin, and dramatically responded to IL-2, showing a potential to be reactivated upon appropriate conditions. These results indicate that persistent T-cell clonal expansion is an important feature of polymyositis.