Abstract
1) The growth from human leukemic bone marrow particles begins with the emigration of cells having the morphologic characteristics of erythrocytic, granulocytic, monocytic and lymphocytic elements. Proliferation of fibroblastic-like cells replaces these elements within 3 to 4 weeks. Various types of immature leukocytes occur in larger numbers, and persist longer, in tissue cultures of human leukemic bone marrow than in bone marrow cultures from patients with no hematological disease.
2) Lymphocytes from either leukemic or non-leukemic bone marrow cultures often appear to enter the cytoplasm of fibroblast-like cells, but those derived from cultures of chronic lymphocytic leukemic bone marrow appeared intracellularly in much larger numbers and persisted there longer. One of the mechanisms of this phenomenon may be the feeder layer principle. Extensive injury of certain fibroblast-like cells in relation to relatively few small lymphocytes suggests the possibility of an autoimmune attack. It is possible that both the lymphocytes and the "target cells" may disintegrate.
3) Two types of multinucleated giant cells have been observed. One type is syncytial in structure, suggesting a viral mechanism of initiation. Another type resembles the polyploid giant cells which are commonly seen in old tissue cultures of whatever origin, and in various malignant diseases in vivo as well as in vitro.
4) At times, poorly differentiated round cells may persist in old fibroblastic cultures. These cells may be derived from the original explant which continued to produce them, or they may originate from fibroblast-like cells reconverted into a morphologically undifferentiated mesenchymal cell type.
