In order to study the pathogenesis of juvenile type chronic myelocytic leukemia (juvenile type CML), we examined the capacity of colony formation in the bone marrow (BM) and the peripheral blood (PB) from 2 children who filled the criteria for juvenile type CML. A new techique of cytochemical examination of all colonies grown in agar gel culture was applied. BM or PB cells were cultured in a single layer using 10% of human placental conditioned medium as the colony stimulating activity (CSA). At the end of culture, the agar gel was stained for esterase activity in response to naphthol AS-D chloroacetate which is positive for granulocytes and/or α-naphthyl acetate which is positive for macrophages.
Tremendously large number of colonies were formed by BM and especially PB cells from the patients. In BM from case 1, colonies exclusively consisting of macrophages (macrophage colonies) were 51% on day 7 of culture and 72% on day 14 respectively. When the leukocyte increased in case 1 from 13,100/mm3 to 30,800/mm3, the number of colonies in PB increased from 17±2 to 396±11/2×105 mononuclear cells and ratio of macrophage colonies to the whole granulocyte-macrophage colonies increased from 0% to 83%. Similar results were obtained from case 2. While macrophage colonies formed by normal BM cells were less than 5% of all colonies on day 7, and these colonies were small in size and of dispersed-type, the macrophage colonies observed in juvenile type CML were very large and of compact-type.
To study the CSA produced by BM cells, juvenile type CML or normal BM cells were embedded in feeder layer of the agar culture and the normal BM cells were superposed in overlayer. On day 7, they formed 1736±171 and 1850±49 clusters/2×105 cells respectively and 99% of clusters were granulocytic. Thus the abnomality of CSA of juvenile type BM was not noted. From these findings, juvenile type CML may be one of panmyelopathy similar to adult type CML. Predominant growth of macrophage in vitro, however, is in marked contrast to granulocytic predominance in adult type CML.
