Characteristics of hematopoietic cell line established from human myelomonocytic leukemia.

The peripheral blood of an acute myelomonocytic leukemia patient has been cultured for 16 months. The culture is at present at the 140th population doupling level. The cultured cells have the characteristics of so-called lymphoblastoid cells and proliferate actively as individual cells in small clusters, or in large clumps consisting of large mononuclear cells. Some of these cells appeare to be lymphoid, but the majority are immature mononuclear cells with a tendency to lobulate. They gave a weakly positive peroxidase reaction at the beginning of cultivation, and have given a strongly positive esterase reaction persistently. The cytoplasm shows ciliary or tail-like projections as the cell matures. Complement (C3) receptor and IgG receptors are found on the cell surface, and active phagocytosis is mannifest. Colloidal iron particles or viable red blood cells attached to the cell membrane suggesting possible differentiation to reticulum cells or macrophages. The cultured cells are mostly diploid but some cells show chromosome abnormality. Herpes type virus was foun in the nucleus, cytoplasma and on the cell membrane. The transplanatation of cultured cells to the cheek pouch of hamsters produced small tumors with histological findings resembling reticulum cell sarcoma.