This immune-competent, conditioning-dependent, tumor model uses systemic hCD19 modified EL4 (EL4[hCD19]) thymoma tumors infused into C57BL6 mice with a knockout murine CD19 (mCD19−/−), knock-in human CD19 (hCD19+/−) phenotype (C57BL6 [mCD19−/− hCD19+/−]) (170). The gene discussed is CD19; the disease is thymoma.