GRANULOCYTE-COLONY-STIMULATING FACTOR INDUCES DIFFERENTIATION AND APOPTOSIS OF CD2, CD7 POSITIVE HYBRID LEUKEMIA-CELLS IN-VIVO AND EX-VIVO

We report a case of a 70-year-old man with a hybrid leukemia treated s uccessfully with granulocyte-colony stimulating factor (G-CSF) combine d with a cytocine arabinoside regimen through the induction of differe ntiation of leukemic cells into monocytoid cells resulting in apoptosi s. The leukemic cells demonstrated a TCR-gamma gene rearrangement, and expressed CD2, CD7, CD33 and G-CSF receptors but not CD11b on the cel l surface nor nonspecific esterase in cytoplasm. Several days followin g the administration of G-CSF, the cells with monocytoid characteristi cs such as CD11b and cytoplasmic non-specific esterase appeared in the peripheral blood replacing the blastic cells. The cells were shown to be derived from the same clone of the leukemic cell because of the id entical TCR-gamma gene rearrangement. The short-term culture of leukem ic cells with G-CSF induced the differentiation into a monocyte lineag e, resulting in apoptosis, Although there is no denying the possibilit y that cytosine arabinoside is partly responsible, our results strongl y suggest that G-CSF plays the main role in differentiation of leukemi c cells into a monocyte lineage inducing apoptosis in vivo in this pat ient. (C) 1997 Elsevier Science Ltd.