Clonal T cell populations scarcely impair patients with rheumatic diseases: a prospective long-term follow up study

Clonal T cell populations are frequently detected in patients with rheumatic diseases. The relevance of this finding is often uncertain, as the clinical spectrum can range from being asymptomatic to T cell leukemia. Former studies suggested that certain anti-rheumatic drugs might influence the course of the clonal T cell populations. A prospective long-term follow up study was performed including patients with rheumatic diseases and clonal T cell populations. Clinical features, adverse events, especially infections and cytopenias, and immunosuppressive medication were assessed. T cell populations were characterized by polymerase chain reaction, flow cytometry and stimulated cell cultures. 28 Patients with rheumatoid arthritis, spondyloarthritis, or giant cell arteritis were prospectively followed for up to 7.6 years. Severe infections or cytopenias (10.7% autoimmune neutropenias) were rare. The clonal T cell populations mostly persisted over time, the tumor burden decreased in the long-term. The cytokine secretion in stimulated T cell cultures did not differ in the subgroup of RA patients with versus without clonal T cells. Clonal T cell populations in patients with rheumatic diseases are common, but are rarely harmful. Feared neutropenia, infections or progression into T cell leukemia could not be detected in the long-term in our cohort.