title: CD40L induces proliferation, self-renewal, rescue from apoptosis, and production of cytokines by CD40-expressing AML blasts.
abstract: OBJECTIVE
  Conflicting experimental and clinical results have been reported regarding the role of CD40 in acute myeloid leukemia (AML). In the present study, we analyzed the capability of CD40L/CD154 to modulate several functional aspects of CD40-expressing AML blasts.
  
  
  METHODS
  After defining the constitutive expression levels of CD40 in a wide panel (n = 67) of AMLs and evaluating the capability of cytokines to modulate its expression, we investigated the effects of CD40 engagement by soluble (s) CD40L on proliferation, self-renewal capacity, apoptosis, homotypic adhesion, and cytokine production of leukemia cells.
  
  
  RESULTS
  CD40 was detected in blast cells from about 37% of AMLs, the highest frequency being documented in monocytic subtypes, and its expression was upregulated or de novo induced by treatment with interleukin (IL)-1alpha, IL-3, IL-4, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-gamma, and tumor necrosis factor-alpha. Exposure of CD40(+) AML blasts to sCD40L resulted in a dose-dependent proliferative response, enhancement of clonogenic growth and self-renewal capacity, and a striking increase in colony size. CD40 engagement was able to rescue AML blasts from apoptosis induced by serum deprivation, as demonstrated by reduced expression of APO2.7 and annexin-V binding, as well as upregulation of the anti-apoptotic protein bcl-x(L). CD40 triggering upregulated cell surface expression of the adhesion molecules CD54, CD58, and CD15 and resulted in homotypic aggregation of leukemia cells at least in part CD54-dependent. An increased production of IL-6 and GM-CSF by CD40(+) AML blasts was also documented upon sCD40L exposure.
  
  
  CONCLUSIONS
  This study indicates a possible involvement of CD40 in the interactions of AML blasts with other growth-sustaining microenvironmental accessory cells and immune effectors, in turn expressing CD40L. Caution in the use of CD40 triggering in immunotherapy of AMLs is also suggested.
authors.affiliation: Clinical and Experimental Hematology Research Unit, I.R.C.C.S., Aviano, Italy. daldinucci@cro.it
authors.forename: Donatella
authors.initials: D
authors.lastname: Aldinucci
authors.forename: Dalisa
authors.initials: D
authors.lastname: Poletto
authors.forename: Paola
authors.initials: P
authors.lastname: Nanni
authors.forename: Massimo
authors.initials: M
authors.lastname: Degan
authors.forename: Maurizio
authors.initials: M
authors.lastname: Rupolo
authors.forename: Antonio
authors.initials: A
authors.lastname: Pinto
authors.forename: Valter
authors.initials: V
authors.lastname: Gattei
mesh_terms: D000208:Acute Disease; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects; D019013:CD40 Antigens / Q000032:analysis / Q000502:physiology; D023201:CD40 Ligand / Q000494:pharmacology / Q000502:physiology*; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D007378:Interleukins / Q000494:pharmacology; D007951:Leukemia, Myeloid / Q000473:pathology*; D051379:Mice; D009363:Neoplasm Proteins / Q000032:analysis / Q000502:physiology; D014411:Neoplastic Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics; D012995:Solubility; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014410:Tumor Stem Cell Assay; D051020:bcl-X Protein
chemical_list: D015703:Antigens, CD; C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D019013:CD40 Antigens; D016207:Cytokines; D015850:Interleukin-6; D007378:Interleukins; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014409:Tumor Necrosis Factor-alpha; D051020:bcl-X Protein; D023201:CD40 Ligand; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor