Spontaneous transplantable lymphatic leukemia in Lewis rat (KPH-Lw-I).

A spontaneous transplantable acute lymphatic leukemia in Lewis rats (KPH-Lw-I) is described. It is transplantable regardless of age and sex in inbred Lewis rats. The leukemic cells are of a normal karyotype. The progress of the disease is very rapid with many similarities to human acute lymphatic leukemia. Attempts to grow these leukemic cells in adult Wistar rats were unsuccessful, but they grow in newborn Wistar rats. During two years about eighty passages were done and the course of the disease was similar to that found in the original Lewis rat. No evidence for B-lymphocyte markers was found on the surface of leukemic cells.