The NKT cells from patients with ITP were observed to inhibit the proliferation of CD4+ T cells in vitro, which may indicate a protective role of NKT cells in ITP.44 Ho et al45 demonstrated that isolated V24 invariant (V24i) CD1d-restricted NKT, a specific subset of NKT cells, was able to kill antigen-presenting cells, suggesting a mechanism by which NKT cells limit T-cell activation and support the protective role of NKT cells in ITP. The gene discussed is CD4; the disease is autoimmune thrombocytopenic purpura.