CD28 and paroxysmal nocturnal hemoglobinuria: They used TCR flow cytometry and CDR-3 analysis to assess clonality of T lymphocytes and found that TCR-Vβ-specific expansions were detected in 10 PNH patients and 14 AA/PNH patients, and among four of them, extreme expansions of one Vβ-subset of CD8+/CD28-/CD56+(effector) phenotype were found, which is very similar to large granulocytic lymphocytic (LGL) leukemia (18); these lines of evidence support the idea that T lymphocyte is involved in the pathogenesis of PNH.