Human glioblastoma tumours and neural cancer stem cells express the chemokine CX3CL1 and its receptor CX3CR1.

Human gliomas represent an unmet clinical challenge as nearly two-thirds of them are highly malignant lesions with fast progression, resistance to treatment and poor prognosis. The most severe form, the glioblastoma multiforme, is characterised by a marked and diffuse infiltration through the normal brain parenchyma. Given the multiple effects of chemokines on tumour progression, aim of this study was to analyse the expression of the chemokine CX3CL1 and of its specific receptor CX3CR1 in 36 human surgical glioma samples, with different degrees of histological malignancy and in glioblastoma-derived neurospheres. Herein we show that both ligand and receptor are expressed at the mRNA and protein levels in most specimens (31/36). While receptor expression was similarly detected in low or high grade tumours, the uppermost scores of CX3CL1 were found in grades III-IV tumours: oligodendrogliomas, anaplastic astrocytomas and glioblastomas. Accordingly, the expression of CX3CL1 was inversely correlated with patient overall survival (p = 0.01). Glioblastoma-derived neurospheres, containing a mixed population of stem and progenitor cells, were positive for both CX3CR1 and for the membrane-bound chemokine, which was further up-regulated and secreted after TNF-IFNγ stimulation. Confocal microscopy of 3D neurospheres showed that the ligand was primarily expressed in the outer layer cells, with points of co-localisation with CX3CR1, indicating that this ligand-receptor pair may have important intercellular adhesive functions. The high expression of CXC3L1 in the most severe forms of gliomas suggests the involvement of this chemokine and its receptor in the malignant behaviour of these tumours.

A novel immunodeficiency characterized by the exclusive presence of transitional B cells unresponsive to CpG.

The objective of this study was to describe a novel form of primary immune disorder characterized by circulating B cells with the exclusive transitional phenotype which fail to respond to CpG stimulation. The 12-year-old male patient suffered from recurrent bacterial infections since infancy. The immunological studies were based on extensive B cell immunophenotyping, humoral in vivo response to different vaccine antigens, and in vitro proliferation and immunoglobulin production after CpG stimulation. Sequence analysis for potentially candidate genes such as IRF8, MyD88, TLR9, T-bet were performed. The patient's serum immunoglobulin levels and the specific antibody response to tetanus toxoid were normal, whereas that to polysaccharide antigens was severely impaired. Flow cytometric analysis showed that almost all patient's peripheral B cells had the transitional phenotype (CD24(bright) CD38(bright) CD27(neg)). Furthermore, the patient's B cells did not proliferate and failed to secrete immunoglobulins after in vitro CpG stimulation. Sequence analysis for TLR9, MyD88, IRF8 and T-bet showed no mutations. To our knowledge, this is the first case of a novel primary immunodeficiency mimicking the clinical phenotype of common variable immunodeficiency, with a peculiar immunological phenotype characterized by normal immunoglobulin serum levels, circulating B cells with the exclusive transitional phenotype unable to respond to CpG stimulation. This defines a novel form of primary immunodeficiency mimicking common variable immunodeficiency in the presence of normal immunoglobulin serum levels.