In conjunction with a terminally differentiated (CCR7− CD45-RA+) effector phenotype, the dominant CD8+ TCR-Vβ+ expansions in T-LGLL patients expressed high levels of CD57, which is thought to indicate replicative senescence as a consequence of antigen-driven proliferation30, and correspondingly low levels of immunoregulatory markers, such as PD-131. The gene discussed is B3GAT1; the disease is T-cell large granular lymphocyte leukemia.