This kind of T cells, known as the GPI specificity, CD1d-restrictive T cells, increased 10 times in PNH patients compared to normal control (48); this proof further supports the idea that T lymphocytes play the role of CTL by targeting GPI molecule by the CD1d(MHC)–TCR complex, and the GPI- HSCs can escape from immune attack, although the specific mechanism is still unclear (Figure 2A). This evidence concerns the gene CD1D and paroxysmal nocturnal hemoglobinuria.