FREQUENT GENE-EXPRESSION OF GRANULOCYTE-COLONY-STIMULATING FACTOR (G-CSF) RECEPTOR IN CD7 PLUS SURFACE CD3- ACUTE LYMPHOBLASTIC-LEUKEMIA

Gene expression of various cytokine receptors in CD7+ acute lymphoblas tic leukemia (ALL) cells in relation to responsiveness to these cytoki nes was examined by reverse transcription polymerase chain reaction an d Northern blot studies. Leukemic cells from all of seven CD7 + ALL pa tients examined fulfilled the criteria for ALL according to the FAB cl assification; surface CD3 was absent in all of these patients, while c ytoplasmic CD3 and/or CD3epsilon mRNA were found in all of them. Sampl es from six of the seven patients at initial disease expressed the gra nulocyte colony-stimulating factor receptor (G-CSFR) gene. Leukemic ce lls with G-CSFR transcripts from one patient at initial disease showed growth response to G-CSF in vitro, and those from two other patients became responsive to G-CSF at relapse. Neither in vitro nor in vivo my eloid differentiation was observed in any samples that responded to G- CSF. Interleukin 3Ralpha (IL-3Ralpha) gene was expressed in samples fr om one patient at initial disease and from two patients at relapse. GM -CSFRbeta gene mRNA was detected in two patients with IL-3Ralpha mRNA. Our results show that the leukemic cells in these CD7 + ALL patients frequently expressed G-CSFR as a functional property, thus calling att ention to the appropriate clinical application of G-CSF for ALL patien ts.