The growth patterns of two transplantable acute leukaemias of spontaneous origin in rats.

The growth pattern and morphology of two transplantable acute leukaemias which arose spontaneously in pure line rats are described. They differ morphologically and on the basis of their behaviour in vivo, such as infiltration of lymphoid organs and presence in thoracic duct lymph, the leukaemia syngeneic to the August strain (referred to as the SAL) appears to be of myeloid type whereas the leukaemia syngeneic to the Hooded strain (referred to as the HRL) resembles acute lymphoblastic leukaemia. The HRL cells, but not the SAL cells, are lysed by murine anti-theta serum plus complement. These two transplantable acute leukaemias appear to be useful animal counterparts ot the human acute leukaemias and may be valuable models for studies on chemotherapy and immunotherapy.