Constitutive activation of distinct BCR-signaling pathways in a subset of CLL patients: a molecular signature of anergy

Marta Muzio, Benedetta Apollonio, Cristina Scielzo, Michela Frenquelli, Irene Vandoni, Vassiliki Boussiotis, Federico Caligaris-Cappio, Paolo Ghia

Research output: Contribution to journalArticlepeer-review


Stimulation through the B-cell antigen receptor (BCR) is believed to be involved in the natural history of chronic lymphocytic leukemia (CLL). Some cases respond to the in vitro cross-linking of surface immunoglobulin (slg) with effective activation. In contrast, the remaining cases do not respond to such stimulation, thereby resembling B cells anergized after antigen encounter in vivo. However the biochemical differences between the 2 groups are ill defined, and in humans the term B-cell anergy lacks a molecular definition. We examined the expression and activation of key molecules involved in signaling pathways originating from the BCR, and we report that a proportion of CLL patients (a) expresses constitutively phosphorylated extracellular signal-regulated kinase (ERK)1/2 in the absence of AKT activation; (b) displays constitutive phosphorylation of MEK1/2 and increased nuclear factor of activated T cells (NF-AT) transactivation; and (c) is characterized by cellular unresponsiveness to slg ligation. This molecular profile recapitulates the signaling pattern of anergic murine B cells. Our data indicate that constitutive activation of mitogen activated protein (MAP) kinase signaling pathway along with NF-AT transactivation in the absence of AKT activation may also represent the molecular signature of anergic human B lymphocytes. CLL cases with this signature may be taken as a human model of anergic B cells aberrantly expanded.

Original languageEnglish
Pages (from-to)188-195
Number of pages8
Issue number1
Publication statusPublished - Jul 1 2008

ASJC Scopus subject areas

  • Hematology
  • Biochemistry
  • Cell Biology
  • Immunology


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