Autoimmune and inflammatory diseases associated with T-cell clonal expansion.

Autoimmune and inflammatory diseases (AID) result from a breakdown of immune tolerance, often driven by T-cell dysregulation and sometimes associated with clonal T-cell expansion. While T-cell large granular lymphocyte leukemia (LGL-L) is a well-defined clonal disorder commonly associated with AID, the clinical relevance of T-cell clones of uncertain significance (T-CUS) remains unclear. We conducted a retrospective multicenter study across six French centers, including patients with persistent circulating clonal T cells associated with AID, confirmed by T-cell receptor gene rearrangement. T-cell clones ≥ 0.5 × 10⁹/L, or low-count clones (.