Background: The chemokine family plays important roles in cell migration and activation. In humans, at least 44 members are known. Based on the arrangement of the four conserved cysteine residues, chemokines are now classified into four subfamilies, CXC, CC, XC and CX3C. Given that zebrafish is an important experimental model and teleost fishes constitute an evolutionarily diverse group that forms half the vertebrate species, it would be useful to compare the zebrafish chemokine system with those of mammals. Prior to this study, however, only incomplete lists of the zebrafish chemokine genes were reported.

The neoplastic environment is generally regarded as an immunosuppressive milieu. However, a group of cancers are characterized by the abundance of tumour-infiltrating lymphocytes (TILs). Here we examined the possible roles of chemokines in the formation of lymphoid stroma in lymphocyte-rich gastric carcinomas (GCs), including EBV(+) cases and conventional GCs. Regardless of EBV positivity, TILs in lymphocyte-rich GCs predominantly expressed CXCR3, while its ligand CXCL9 was abundantly expressed by stromal cells and a portion of cancer cells. CXCL9(+) stromal cells were judged to include dendritic cells, because they partly co-expressed fascin, DC-sign, CD83, DC-lamp or HLA-DR. T cells in close contact with CXCL9(+) cells showed frequent labelling of Ki-67 (approximately 10%), suggesting the immunostimulatory activity of CXCL9(+) stromal cells. The T-cell zone of the regional lymph nodes of lymphocyte-rich GCs also abounded with CXCR3(+) T cells and CXCL9(+) stromal cells. This indicated a close similarity between cancer stroma and regional lymph nodes of lymphocyte-rich GCs. Quantitative RT-PCR also confirmed the strong expression of CXCR3, CXCL9 and IFNgamma in lymphocyte-rich GCs. In contrast, conventional GCs contained less abundant CXCR3(+) T cells and few CXCL9(+) stromal cells. Collectively, the CXCL9-CXCR3 axis plays a pivotal role in the formation of lymphoid stroma in lymphocyte-rich GCs. Given similar findings in the regional lymph nodes, the lymphoid stroma of lymphocyte-rich GCs may represent a tertiary lymphoid tissue with predominantly Th1-shifted immune responses.

Classical Hodgkin's disease (HD) is characterized by rare neoplastic Hodgkin and Reed-Sternberg (H-RS) cells within abundant reactive cellular backgrounds. In most cases, H-RS cells originate from the B-cell lineage, but their immunophenotypes are unusual. Here we newly found frequent expression of chemokine receptors CXCR6 and CCR10 and their respective ligands CXCL16 and CCL28 in HD-derived cell lines. CCR10 is known to be selectively expressed by plasma cells, whereas CCL28 attracts eosinophils via CCR3 and plasma cells via CCR10 and CCR3. Therefore, we examined their expression in HD tissues by immunohistochemistry. We found that H-RS cells in 15 of 19 cases were positive for CCL28. Among them, seven cases were also positive for CCR10, suggesting a potential autocrine effect. In situ hybridization confirmed the expression of CCL28 mRNA in H-RS cells. The CCL28 positivity in H-RS cells did not significantly correlate with that of LMP-1, CCL17, CCL22, or CCL11. However, it significantly correlated with the background accumulation of eosinophils, plasma cells, and CCR10+ cells. Thus, the production of CCL28 by H-RS cells may play a major role in tissue accumulation of eosinophils and/or plasma cells in classical HD. The frequent expression of CCR10 in H-RS cells themselves also supports their close relationship to plasma cells.

Age-related Epstein-Barr virus-positive (EBV+

SummaryAccumulation of plasma cells in the synovium is one of the diagnostic hallmarks in the histopathological manifestations of rheumatoid arthritis (RA). This seems to be prominent even prior to significant B cell infiltration and/or formation of lymphoid follicles in the synovium. To clarify the mechanism of early plasma cell accumulation, we examined in situ expression of chemokines and their receptors using synovial targeting biopsy specimens, which were obtained under arthroscopy from early RA patients. By immunohistochemical staining, plasma cells were found to express a chemokine receptor CXCR3, while synovial fibroblasts in the synovial sublining regions expressed its ligand, Mig/CXCL9. By reverse transcription-polymerase chain reaction (RT-PCR), using targeted lesions of synovial tissues obtained by laser capture microdissection, expression levels of Mig/CXCL9 in the synovial sublining regions were remarkably high and were likely to be associated with interferon (IFN)-g g g g expression. Furthermore, cultured synovial fibroblasts were confirmed to produce Mig/CXCL9 upon stimulation with IFN-g g g g . Our results indicate that in the early stage of RA, plasma cells expressing CXCR3 may be recruited directly from the circulation into the synovial sublining regions by its ligand, Mig/CXCL9, produced by synovial fibroblasts.