Little is known regarding the immunobiology of regulatory T (Treg) cells in hematopoietic malignancies, particularly in chronic lymphocytic leukemia (CLL). In the present study, we showed that the frequencies of CD8(+) and CD4(+) Treg cells were significantly increased in progressive as compared with indolent CLL patients and normal subjects. Enriched CD4(+) Treg cells induced a similar level of inhibition in polyclonally activated B cells and effector T cells from CLL patients and normal subjects. Our results suggest that the increase in circulating Treg cells may result in downregulation of tumor-specific immune response, leading to tumor expansion and disease progression.
Recent molecular investigations have demonstrated over-expression of a large number of tumor associated antigens (TAAs) in a variety of malignancies. Over-expression of ROR1 gene, a member of the receptor tyrosine kinase family, has recently been reported in B-cell chronic lymphocytic leukemia. Wilms' tumor gene 1 (WT1) has long been known as a universal TAA expressed in a variety of solid and hematopoietic malignancies. In the present study, the expression profile of ROR1 and WT1 was investigated in different immunophenotypic subsets of B-cell acute lymphoblastic leukemia (B-ALL) patients. RT-PCR method was used to determine the ROR1 and WT1 genes expression in bone marrow (BM) and peripheral blood (PB) samples from 51 newly diagnosed Iranian B-ALL patients. Isolated tumor cells from all patients were immunophenotyped by flow cytometry. Based on immunophenotypic results, our B-ALL patients were classified in four differentiation subsets; Pro-B (n = 7), Pre-B I (n = 29), Pre-B II (n = 13) and Immature/mature B-ALL (n = 2). Although ROR1 was over-expressed in more mature subsets (16.7%, 42.9%, 45.5% and 100%, respectively), WT1 was more represented in immature subsets of B-ALL patients (57.1%, 64.3%, 38.5% and 0%, respectively). Comparison of the frequency of ROR1 and WT1 positive samples at each immunophenotypic subtype revealed statistically significant difference only in Pre B I subtype (p = 0.02). Our results suggest that expression of ROR1 and WT1 in B-ALL is associated with the differentiation stage of the leukemic cells.
The Wnt molecules are a family of secretory glycoproteins implicated in proliferation and differentiation of both normal and malignant cells. Despite extensive investigation of the WNT genes expression profile in various tumors, little is known about their expression in chronic lymphocytic leukemia (CLL). In this study, the expression profile of 14 WNT genes was investigated in a large number of Iranian patients with CLL. Semi-quantitative RT-PCR was performed on peripheral blood leukemic cells obtained from 62 patients with CLL. Peripheral blood mononuclear cells isolated from 11 age matched normal subjects served as control to determine baseline expression level of these genes. Our results have demonstrated significant up-regulation of WNT-3, WNT-4, WNT-5B, WNT-7B, WNT-9A, WNT-10A, and WNT-16B in patients with CLL compared to normal subjects (p < 0.05 to p < 0.0001). WNT gene expression analysis in different CLL subtypes showed a similar pattern of expression in progressive and indolent clinical subtypes. Over-expression of WNT-5A and WNT-9A genes was observed in patients with no mutation in their immunoglobulin (Ig) variable region heavy chain (Ig VH) genes compared to those with mutated Ig VH genes. Comparison between patients expressing VH1 (n = 9), VH3 (n = 40) and VH4 (n = 12) gene families, revealed down-regulation of WNT-3 and WNT-9A in VH3 positive patients. Our results indicate up-regulation of many members of the WNT gene family in CLL suggesting involvement of the Wnt canonical and/or noncanonical signaling pathways in CLL tumorigenesis.
Viruses and other microorganisms express specific pathogen-associated molecular patterns that are recognized by cell surface or endosome-associated Toll-like receptors (TLR). There are many examples of viruses that have developed strategies to modulate TLR signaling through the use of viral or cellular molecules. Epstein-Barr virus (EBV) has recently been found to display a complex interaction with TLR. The aim of this study was to asses the effect of EBV infection on proliferative capacity of TLR7/8 and 9 agonist and CD40 ligand (CD40L) in normal B lymphocytes. Our results demonstrate that EBV induces a significant inhibition in proliferative response to TLR7/8 (P < 0.004) and TLR9 (P < 0.000) agonists but not to CD40L stimulation in enriched human normal B lymphocytes. Similar inhibitory effect was also observed in B lymphocytes prestimulated with the TLR agonists, implying that the suppressive effect is not due to downregulation of TLR protein expression by EBV. EBV infection did not induce apoptosis and did not downregulate TLR7/8 mRNA expression in B lymphocytes. Our results suggest that EBV might be able to evade the immune system by modulation of the TLR signaling pathway.
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