In several cell lines, PaCS development follows cell differentiation/activation by trophic factors and cytokines, such as GM-CSF and IL-4 for DCs, IL-2 and IL-15 for NK cells, or thrombopoietin, IL-6 and IL-11 for megakaryocytes in type 2 thrombocytopenia [18]. The gene discussed is IL15; the disease is thrombocytopenia 2.