Kazutaka Uehira

Interferon-α and Interleukin-12 Are Induced Differentially by Toll-like Receptor 7 Ligands in Human Blood Dendritic Cell Subsets

Dendritic cells (DCs) play a crucial role in the immune responses against infections by sensing microbial invasion through toll-like receptors (TLRs). In humans, two distinct DC subsets, CD11c− plasmacytoid DCs (PDCs) and CD11c+ myeloid DCs (MDCs), have been identified and can respond to different TLR ligands, depending on the differential expression of cognate TLRs. In this study, we have examined the effect of TLR-7 ligands on human DC subsets. Both subsets expressed TLR-7 and could respond to TLR-7 ligands, which enhanced the survival of the subsets and upregulated the surface expression of costimulatory molecules such as CD40, CD80, and CD86. However, the cytokine induction pattern was distinct in that PDCs and MDCs produced interferon (IFN)-α and interleukin (IL)-12, respectively. In response to TLR-7 ligands, the Th1 cell supporting ability of both DC subsets was enhanced, depending on the cytokines the respective subsets produced. This study demonstrates that TLR-7 exerts its biological effect in a DC subset-specific manner.

Alteration of peripheral blood dendritic cells in patients with primary Sjögren's syndrome.

OBJECTIVE We recently identified 3 fractions of human peripheral blood (PB) dendritic cells (DC), including the monocyte-associated fractions 1 and 2 (CD1a+,CD11c+ and CD1a-,CD11c+, respectively) and the lymphoid-associated fraction 3 (CD1a-,CD11c-). We attempted to determine whether these fractions were altered in Sjögrens syndrome (SS). METHODS We examined 23 patients with primary SS and 22 normal control subjects. DC were purified from PB and analyzed by flow cytometry. Immunohistochemical staining of labial salivary glands of SS patients was performed with monoclonal antibodies against fascin, which is known to be specific for DC. RESULTS The total numbers of PB DC and fraction 1 DC were decreased in SS. Immunohistochemical staining demonstrated that fascin+,CD11c+,HLA-DR+ mononuclear cells were present and scattered among numerous fascin-hyperfiltrating cells in SS patients. Interferon-gamma (IFNgamma)-producing Th1 cells were shown to be increased in both PB and salivary glands of patients, indicating the presence of general IFNgamma-producing Th1 polarization in SS. Furthermore, numbers of Thl cells were increased when naive T cells were cocultured with fraction 1 DC in vitro. CONCLUSION These findings suggest selective trafficking of fraction 1 DC into focal sites of inflammation and subsequent promotion of Th1 balance, suggesting a novel pathogenesis of SS.

Hodgkin's Reed‐Sternberg cell line (KM‐H2) promotes a bidirectional differentiation of CD4+CD25+Foxp3+ T cells and CD4+ cytotoxic T lymphocytes from CD4+ naive T cells

A recent report revealed that a large population of Hodgkins lymphoma‐infiltrating lymphocytes (HLILs) consisted of regulatory T cells. In this study, we cocultured CD4+ naive T cells with KM‐H2, which was established as a Hodgkins Reed‐Sternberg cell line, to clarify their ability to induce CD25+Forkhead box P3+ (Foxp3+) T cells. The characteristic analyses of T cells cocultured with KM‐H2 revealed the presence of CD4+CD25+ T cells. They expressed CTLA‐4, glucocorticoid‐induced TNFR family‐related gene, and Foxp3 and could produce large amounts of IL‐10. Conversely, KM‐H2 also generated CD4+ CTLs, which expressed Granzyme B and T cell intracellular antigen‐1 in addition to Foxp3+ T cells. They exhibit a strong cytotoxic effect against the parental KM‐H2. In conclusion, KM‐H2 promotes a bidirectional differentiation of CD4+ naive T cells toward Foxp3+ T cells and CD4+ CTLs. In addition to KM‐H2, several cell lines that exhibit the APC function were able to generate Foxp3+ T cells and CD4+ CTLs. Conversely, the APC nonfunctioning cell lines examined did not induce both types of cells. Our findings suggest that the APC function of tumor cells is essential for the differentiation of CD4+ naive T cells into CD25+Foxp3+ T cells and CD4+ CTLs and at least partly explains the predominance of CD25+Foxp3+ T cells in HLILs and their contribution to a better prognosis. Therefore, in APC‐functioning tumors, including classical Hodgkin lymphomas, which generate Foxp3+ T cells and CD4+ CTLs, these T cell repertories play a beneficial role synergistically in disease stability.

A Hodgkin’s Disease Cell Line, KM-H2, Shows Biphenotypic Features of Dendritic Cells and B Cells

The origin of Reed-Sternberg (RS) cells, the neoplastic cells of Hodgkin’s disease, has long remained controversial. Dendritic cells (DCs) are highly specialized antigen-presenting cells that have the unique capacity to prime naive T cells, and they may be progenitors of RS cells in a population of Hodgkin’s disease cells. In this study, the KM-H2 cell line, previously established from a patient with Hodgkin’s disease of mixed cellularity, was reevaluated for its cellular derivation, particularly in terms of DCs. KM-H2 cells were demonstrated to carry the newly proposed DC-associated molecules fascin, CD83, and DEC-205, as well as costimulatory molecules such as CD40, CD80, and CD86. In addition, KM-H2 cells were shown to be able to potently stimulate peripheral blood T cells and to have the strong endocytotic activity of fluorescein isothiocyanate—dextran. On the other hand, KM-H2 cells were shown to have variable-diversity-joining recombination of the immunoglobulin H gene, although they did not express any subclasses of immunoglobulin and they were negative for CD79a and CD79b. In addition, KM-H2 cells produced the messenger RNA of thePax-5 gene.These findings lead to a hypothesis that KM-H2 cells originated from the cells that had differentiated through the possible common DC—B-cell progenitors along the newly proposed pathway.

HLA Typing of a Family with Systemic Lupus Erythematosus

Although systemic lupus erythematosus (SLE) is a representative collagen disease, the etiology remains unclear. However, both genetic and environmental factors seem to be involved. Based on serological studies, associations between certain human leukocyte antigens and many autoimmune diseases have long been suggested. Regarding the genetic aspects of SLE, the HLA haplotype is regarded as a potentially important factor, although its role remains controversial. Recently, we examined three family members who had SLE with an identical HLA haplotype.