title: Biological characteristics of CD7 positive acute myelogenous leukaemia.
abstract: We studied the biological characteristics of CD7+ acute myelogenous leukaemia (AML). We diagnosed nine out of 88 consecutive AML cases as CD7+ AML based on myeloperoxidase positivity and surface antigen expression. In eight of these nine cases more than 20% of leukaemic blasts were found to coexpress both CD7 and a myeloid-associated antigen, CD33, by a two-colour flow-cytometric assay, while in the remaining case more than 90% of blasts were positive for CD7 and myeloperoxidase. CD7+ AML was most frequently observed in M1 among AML subtypes according to the FAB classification. An early stage-specific antigen, CD34 was also expressed on leukaemic blasts from eight of these nine cases. Neither the T-cell receptor (TcR)-beta nor the TcR-gamma gene was clonally rearranged in any of the cases. We then studied the proliferative responses to stimulation by various growth factors. Among interleukin-3 (IL-3), granulocyte/macrophage colony-stimulating factor (GM-CSF), and granulocyte-CSF (G-CSF), IL-3 showed the strongest stimulatory effect on DNA synthesis and leukaemic blast colony formation in 8/9 and 6/8 CD7+ AML cases examined, respectively. On the other hand, the strongest stimulatory effect exerted by IL-3 on blast colony formation was observed in only six out of the 33 CD7- AML cases examined. Furthermore, CD7+ AML blasts could proliferate in response to stem cell factor (SCF); SCF alone showed stimulatory effects on blast colony formation (7/8 cases), and in 5/7 SCF-responding cases, stimulatory effects of SCF were more potent than those of IL-3. In addition, SCF enhanced blast colony formation synergistically with IL-3 in four of these seven cases. These data suggest that progenitor cells of CD7+ AML may possess the biological properties characteristic of immature haematopoietic stem cells.
mesh_terms: D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000032:analysis*; D019011:Antigens, CD7; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D004273:DNA, Neoplasm / Q000096:biosynthesis; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D016130:Immunophenotyping; D007377:Interleukin-3 / Q000494:pharmacology; D015470:Leukemia, Myeloid, Acute / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D009195:Peroxidase / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D014410:Tumor Stem Cell Assay
chemical_list: D015703:Antigens, CD; D019011:Antigens, CD7; D000945:Antigens, Differentiation, T-Lymphocyte; D004273:DNA, Neoplasm; D007377:Interleukin-3; D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D009195:Peroxidase