Experimental studies on reticulosarcoma.

By AKIRA S. KA IoTo, I\I.D. I x A P1IEVIOUS PAPER on exj)erimental leukemia’ the author has demonstrated that various kinds of human leukemias could he transmitted serially to fowls 1w cell-free filtrates. Liver emulsions (lerive(i form 7 cases of leukemia (acute ttlRl chronic myeloid or lymphatic leukemia, chloroleukemia, aleukemic lymphatic leukemia afl(1 myelosis erythraemica,2 were administered to each series of white leghorns intravenously, occasionally intracutaneously or intramuscularly. Over I ,00f) fowls were tested in the course of experiments extending over a period of four to six years an(l the following major results were obtained: 1. Lesions produced in fowls were found to b either (a) myelosarcoma, myelosis and myeloid metaplasia or (h) reticulosarcoma, reticulosis and related con(litions. 2. These changes presented themselves without regar(l to the nature of the materials used for inoculation. Hyperplasia of the immature myeloid tissue or that of the reticulo-endothelial cells can arise in one generation of the same strain, and in the next generation either the former or the latter may occur. 3. Often greyish white tumors were noted, ranging in size from those as large as a sparrow’s egg in myelosarcoma to a hen’s egg in reticulosarcoma. 4. T he liver showed lesions most frequently, followed by the spleen, bone marrow, kidney and rarely the heart and skin. Pathologic changes in the liver, spleen an(l bone marrow were not always found simultaneously; often one or two of these organs were totally free, contrary to cases of the spontaneous chicken leukosis. 5. Marked anemia was usually absent and the blood picture was characterized by leukopenia without immature cells. Throughout our experiments no evidence of erythroleukosis was encountered. This is in striking contrast to the experience of others with chicken leukosis. 6. In each series hemorrhagic diathesis manifested itself more or less, resulting sometimes in death (lue to hemorrhage. 7. The causative agent passed through Chamberland L1, L2, L3 filters. 8. The agent increased in pathogenicity when cultured on the chorio-allantoic membrane of chick embryo. On these grounds I believe that there is no possibility of confusion with infective agents of chicken leukosis, and that human leukemia is an infectious neoplastic (hsease caused by a specific virus. In addition, we have noted the peculiar phenomenon in each series of experiments that different forms of the lesions (hyperplasia of myeloid tissue and of