Abstract
Two monoclonal antibodies (MoAbs), H-25 and H-366, shown previously to react with human peripheral blood large granular lymphocytes with natural killer (NK) cell activity and some peripheral blood monocytes, have now been shown to also react with a significant proportion of the myeloid and erythroid precursor cells in human bone marrow and peripheral blood. In FACS IV cell sorting and immune rosetting of bone marrow cells, the antigens recognized by H-25 and H-366 were found to be expressed on most blasts and promyelocytes but sequentially fewer of the more mature cells of the myeloid lineage. Both antigens were also found on most monocytes but only a minor proportion of lymphoid and nucleated red cells in the bone marrow. In vitro assays detecting hematopoietic colony-forming units revealed that these antigens are expressed by virtually all mature erythroid colony-forming units (day-7 CFU-E), and the majority of the more primitive erythroid burst forming units (day-14 BFU-E). H-25 but not H-366 was also found on a variable proportion of the day-7 and day-14 granulocytic/monocytic colony- forming units (CFU-GM) in the bone marrow. The same type of precursor cells are also found in the H-25 and H-366 positive cell populations isolated from peripheral blood. In preliminary testing of cells from acute leukemic patients, FACS analysis showed that both antigens are also expressed on leukemic cells from patients with T cell acute lymphocytic leukemia and with myeloid leukemias. These studies demonstrate that the H-25 and H-366 positive NK cells in the peripheral blood retain some of the cell surface properties of early hematopoietic precursor cells, thus providing further evidence supporting the bone marrow origin of NK cells.
