Establishment of a human t(4;11) leukemia in severe combined immunodeficient mice and successful treatment using anti-CD19 (B43)-pokeweed antiviral protein immunotoxin.

Human acute leukemia, with a chromosomal translocation involving chromosomes 4 and 11, t(4;11)(q21;q23), is the most common form of leukemia in infants and responds very poorly to conventional therapy. A human CD19+ mixed-lineage leukemia cell line with a t(4;11)(q21;q23) translocation, RS4;11, disseminated and proliferated in the hematopoietic tissues and other organs of mice with severe combined immunodeficiency in a manner similar to that observed in humans and killed 100% of the animals. The anti-CD19(B43)-pokeweed antiviral protein immunotoxin selectively inhibited clonogenic RS4;11 cells in vitro, markedly reduced the burden of disseminated leukemia of severe combined immunodeficient mice, and, most importantly, resulted in the long-term survival of treated animals. This severe combined immunodeficient mouse model should be useful for the design of more effective treatment strategies for refractory human leukemias.