Bone Marrow Depression in Murine Leukæmia

Abstract

ON occasions the appearance of leukæmia in humans is preceded by a period of bone marrow depression and evidence of aplastic anæmia¹. Such findings may persist for some time and may result in confusion in diagnosis or the leukæmia is regarded as an aleukæmic form of the disease. In a group of A strain mice at present being studied for the effects of intermittent X-radiation, it was noted that while, as expected, the mice developed lymphocytic neoplasms and leukæmia in response to the irradiation, a significant proportion of animals with these diseases also showed aplastic or hypoplastic changes in their marrows when examined at autopsy. This hypoplasia initially affected the erythropoietic cells (Fig. 1), but as it became more severe appeared to affect all elements of the bone marrow (Fig. 2). The incidence of lymphoid leukæmia and the various forms of that disease in this group of mice have been considered elsewhere² ; this communication presents some of the features of the marrow depression which is seen in the mice with lymphoma and lymphoid leukæmia. Table 1 shows the distribution of marrow hypoplasia or aplasia in the different groups of mice. A fuller discussion of the incidence of this condition, its time of appearance and relationship to radiation dose will be presented elsewhere. However, it is obvious that two factors, apart from radiation, appear to increase the incidence of bone marrow depression ; they are femaleness and the absence of a thymic tumour or enlargement.