Transplantation and morphological studies of primary and passaged murine radiation-induced myeloid leukaemias.

Myeloid leukaemia can be induced reproducibly in CBA/H male mice following X-irradiation. After serial passage of the leukaemic cells into syngeneic recipients, they grow faster and require fewer cells for a take. Transplantation of primary leukaemias requires high cell doses unlike passaged lines derived from them. Passaging at low cell doses retains their primary-like growth and morphological properties. It would seem that these low cell dose passages may be a more useful model which can be used for investigating the biology and therapeutic responses of myeloid leukaemia than routinely passaged cell lines.