Although the CpG-B motif is an established immunostimulatory agent, its direct effect on normal and tumor B cells seems to differ: CpG-ODNs stimulate proliferation of healthy B cells, activate their production of polyreactive immunoglobulins, and protect them from apoptosis [6–8]. On the other hand, these ODNs predominantly activate Selleck Adriamycin malignant B cells and then increase

the rate of cell death, thus reducing survival of malignant B cells over time [9–11]. Different types of non-Hodgkin B-cell lymphomas differ in their responsiveness to CpG-DNA, and only limited information is available [9] about the sensitivity of malignant B cells to this DNA motif according to their in vivo microenvironment, particularly in immune sanctuaries such as the brain and eyes. Unlike systemic lymphoma, Selonsertib supplier primary cerebral lymphoma (PCL) and primary

intraocular lymphoma (PIOL) are subsets of primary central nervous system lymphoma (PCNSL), and they affect immunologically privileged organs. Both usually appear as a diffuse large B-cell non-Hodgkin lymphoma in which malignant lymphoid cell types not normally present in the brain or eye are detected [12]. The internal tissues of the brain and eye are usually protected from the inflammatory processes mediated by the immune system. In this study, we compare the effect of CpG-ODNs on cerebral and ocular diffuse large B-cell lymphoma and on subcutaneous lymphomas (SCL). We show that A20.IIA murine B-cell lymphoma expressed Staurosporine high levels of endogenous TLR9 protein that produced an antiproliferative effect when stimulated in vitro by CpG-ODNs. A proapoptotic effect accompanied this reduced proliferation. In vivo local administration had a similar antitumor effect on subcutaneous and cerebral lymphomas. However, local administration of CpG-ODNs in a PIOL mouse model did not produce an antitumor effect. In vitro experiments with supernatant from ocular lymphoma samples demonstrated that the molecular microenvironment of PIOL counteracts the direct antiproliferative effect of

CpG-ODNs on lymphoma B-cells. These findings show that cerebral and ocular tumor cells differ in their responsiveness to CpG stimulation according to the tumor environment. The microenvironment of the eye must be further characterized to identify the negative regulators. Methods Reagents Nuclease-stable PIK-5 phosphorothioate-modified CpG 1826 (CpG) with 5_-TCCATGACGTTCCTGACGTT (the nucleotides in bold represent the immunostimulatory CpG sequences), fluorescein isothiocyanate (FITC)-conjugated CpG 1826 ODNs, and control 1826 ODN with 5_-TCCATGAGCTTCCTGAGCTT were purchased from InvivoGen (Cayla, France). Cells A20.IIA is an FcγR-negative clone originating from the A20-2 J B-cell lymphoma line [13]. For in vivo experiments, A20.IIA cells were transfected by an electroporation system with the green fluorescent protein (GFP) gene. These cells, hereafter referred to as A20.IIA or A20.