Childhood leukemia with simultaneously expressed myeloid and lymphoid markers suggesting stem cell origin.

A case study is presented of a leukemic patient whose cells express markers of both myeloid and lymphoid cells. Cells were identified from bone marrow which expressed either myeloid antigens, lymphoid antigens, or both myeloid and lymphoid antigens, indicating a possible common stem cell capable of differentiating along either a lymphoid or myeloid cell lineage. Using specific monoclonal antibodies, 40-70% of the cells were reactive with anti-T-cell antibodies, 50% of the cells were reactive with antibodies to the common ALL antigen (CALLA), and 80-90% of the cells were reactive with antibodies directed against myeloid antigens. Using double staining techniques, some cells were found to demonstrate only myeloid markers; others, only lymphoid markers; and others, both myeloid and lymphoid markers. These results suggest that a common stem cell is capable of differentiating along both lymphoid and myeloid lineages.