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

Cross reactivity of an alloantigen present on normal cells with the tumour-specific transplantation-type antigen of the acute myeloid leukaemia (SAL) of rats.

Resistance can be induced in the syngeneic host (August rats) to a myelogeneous leukaemia of spontaneous origin, called SAL, by immunization with allogeneic cells derived form both normal and malignant tissues obtained from the Hooded rat strain. Serological experiments support the conclusion that the antigen involved-referred to as "Ho-SAL"-has the properties of a tumour specific transplantation-type antigen for SAL cells but is a widely expressed alloantigen found in both normal and malignant cells derived from Hooded rats. Antisera to it can be raised in Wistar rats