Derivation of leukemic plasmacytoid dendritic cells coexpressing a progenitor cell surface antigen, CD117, without interferon-α production

CD4(+)CD56(+) lineage negative malignancy has recently been considered as plasmacytoid dendritic cell (PDC) leukemia/lymphoma. We investigated immunophenotypic and functional characterizations of PIDC leukemic cells in one case. Lineage markers were all negative except partially positive CD1 1c and po ' sitive CD1 17, indicating malignant cells were leukemic PDCs coexpressing myeloid and progenitor cell surface antigens. Leukemic PDCs cultured with IL-3 increased in size and expression of CD1 1c, CD40 and HLA-DR, although the cells cultured with IL-2 or GM-CSF showed little proliferation. Furthermore, CD40 ligation after IL- 3 stimulation yielded morphological changes such as expression of dendritic process. These findings showed that malignant cells were consistent with leukemic PDCs. However, secretion of interferon-a was not detected in leukemic PDCs with the stimulation of CpG ODN or inactivated herpes simplex virus-1.