Kenji Tadokoro

Diesel-exhaust particulates inoculated by the intranasal route have an adjuvant activity for IgE production in mice

Our previous study indicated that the IgE antibody responses in mice immunized with intraperitoneal injection of the antigens mixed with diesel-exhaust particulates (DEP) were higher than those in the animals immunized with the antigens alone. We examined the adjuvant activity of DEP inoculated by the intranasal route, i.e., the natural entrance of DEP. In 3-week interval immunization, the IgE antibody responses in mice immunized with intranasal inoculation of ovalbumin (OA) mixed with DEP were higher than responses in the animals immunized with OA alone. DEP had an adjuvant activity for anti-OA IgE antibody production, even in a small dose such as 1 micrograms administered with a 3-week interval. Also in 1-week interval immunization, the enhancing effect of DEP on anti-OA IgE antibody production was demonstrated when mice were immunized with intranasal inoculation of OA and DEP. The possibility cannot be excluded that DEP, which are kept buoyant in the environmental atmosphere of urban districts, may exert an adjuvant activity for IgE antibody production after being inhaled into the human body and have some relation to the mechanism of the outbreak of allergic rhinitis caused by pollens in Japan.

Sequence-based association analysis of HLA class I and II alleles in Japanese supports conservation of common haplotypes

Abstract Alleles of HLA-A, B, C, DRB1, DQB1, and DPB1 loci were fully determined in 117 healthy Japanese. A*2402, A*3303, A*1101, A*0201, B*4403, B*5201, Cw*0102, Cw*1403, Cw*0304, Cw*0702, Cw*0801, and Cw*1202 showed frequencies of over 10%. Multi-locus haplotype frequencies were estimated by the maximum likelihood method. Strength of association between C and B loci was comparable with that between DRB1 and DQB1 loci. Alleles unidentified by a serological method and having very similar nucleotide sequences (A2: A*0201, A*0206, A*0207, B61: B*4002, B*4006) were carried by different haplotypes. Several frequent five-locus haplotypes were identified including A*3303-Cw*1403-B*4403-DRB1*1302-DQB1*0604, and A*2402-Cw*1202-B*5201-DRB1*1502-DQB1*0601. These sequence-based haplotypes corresponded to serology-based common haplotypes which have already been described in Japanese. These findings indicate that common HLA haplotypes consist of particular sets of HLA alleles and that these haplotypes have been conserved through recent human evolution.

Infectivity of blood components with low hepatitis B virus DNA levels identified in a lookback program

BACKGROUND: Japanese Red Cross (JRC) blood centers implemented anti‐hepatitis B core antigen (HBc) screening in 1989 and 50‐minipool (MP)‐nucleic acid testing (NAT) in 2000. A systematic lookback study has been conducted to determine the hepatitis B virus (HBV) transmission risk of donations drawn in the pre‐hepatitis B surface antigen (HBsAg) and/or MP‐NAT window phase and by donors with occult HBV infection.

TGF-β1 Reciprocally Controls Chemotaxis of Human Peripheral Blood Monocyte-Derived Dendritic Cells Via Chemokine Receptors

We examined the effect of TGF-β1 on the chemotactic migratory ability of human monocyte-derived dendritic cells (DCs). Treatment of immature DCs with TGF-β1 resulted in increased expressions of CCR-1, CCR-3, CCR-5, CCR-6, and CXC chemokine receptor-4 (CXCR-4), which were concomitant with enhanced chemotactic migratory responses to their ligands, RANTES (for CCR-1, CCR-3, and CCR-5), macrophage-inflammatory protein-3α (MIP-3α) (for CCR-6), or stromal cell-derived growth factor-1α (for CXCR-4). Ligation by TNF-α resulted in down-modulation of cell surface expressions of CCR-1, CCR-3, CCR-5, CCR-6, and CXCR-4, and the chemotaxis for RANTES, MIP-3α, and stromal cell-derived growth factor-1α, whereas this stimulation up-regulated the expression of CCR-7 and the chemotactic ability for MIP-3β. Stimulation of mature DCs with TGF-β1 also enhanced TNF-α-induced down-regulation of the expressions of CCR-1, CCR-3, CCR-5, CCR-6, and CXCR-4, and chemotaxis to their respective ligands, while this stimulation suppressed TNF-α-induced expression of CCR-7 and chemotactic migratory ability to MIP-3β. Our findings suggest that TGF-β1 reversibly regulates chemotaxis of DCs via regulation of chemokine receptor expression.

Analysis of Human Vα24+ CD4+ NKT Cells Activated by α-Glycosylceramide-Pulsed Monocyte-Derived Dendritic Cells

Human Vα24+ NKT cells with an invariant TCR (Vα24-JαQ) have been shown to be specifically activated by synthetic glycolipids such as α-galactosylceramide and α-glucosylceramide in a CD1d-restricted and Vα24 TCR-mediated manner. We recently characterized Vα24+ CD4− CD8− double negative (DN) NKT cells using α-galactosylceramide-pulsed monocyte-derived dendritic cells. Here, we compare Vα24+ CD4+ NKT cells with human Vα24+ DN NKT cells from the same donor using α-galactosylceramide-pulsed monocyte-derived dendritic cells. Human Vα24+ CD4+ NKT cells were phenotypically and functionally similar to the human Vα24+ DN NKT cells characterized previously. Both of them use Vα24-JαQ-Vβ11 TCR and express CD161 (NKR-P1A), but not the other NK receptors tested so far. They also produce cytokines such as IL-4 and IFN-γ, and, in regard to IL-4 production, Vα24+ CD4+ NKT cells produce more IL-4 than Vα24+ DN NKT cells. The cells exhibit marked cytotoxic activity against the U937 tumor cell line, but not against the NK target cell line, K562. Although at least some of the factors responsible for the stimulation of Vα24+ NKT cells have been clarified, little is known regarding the killing phase of these cells. Here we show that the cytotoxic activity of Vα24+ NKT cells against U937 cells is mediated mainly through the perforin pathway and that ICAM-1/LFA-1 as well as CD44/hyaluronic acid interactions are important for the effector phase of Vα24+ NKT cell-mediated cytotoxicity against U937 cells.

IL-12 Responsiveness and Expression of IL-12 Receptor in Human Peripheral Blood Monocyte-Derived Dendritic Cells

We analyzed the expression of IL-12Rβ1 and IL-12Rβ2 and the role of IL-12 in the activation of monocyte-derived dendritic cells (DCs) via IL-12Rβ1-mediated signaling events. Flow cytometric analysis revealed that IL-12Rβ1 was expressed in T cells, Con A blasts, and monocyte-derived DCs, but not in monocytes, while its transcript was detected in all of these cell types. Transcriptional expression of IL-12Rβ2 was observed in T cells, Con A blasts, and monocyte-derived DCs, but not monocytes. The ligation of DCs as well as Con A blasts by IL-12 induced the production of GM-CSF, IL-1β, IL-6, TNF-α, and IFN-γ at the transcription levels. Furthermore, stimulation of DCs with IL-12 induced IL-12p40 transcript, but not IL-12p35 transcript, whereas this stimulation caused the expressions of both transcripts in Con A blasts. Stimulation of DCs with IL-12 caused a tyrosine phosphorylation of several intracellular proteins, and the pattern of these events were distinct from those of IL-12-stimulated Con A blasts. IL-12 also induced tyrosine phosphorylation of IL-12Rβ1 as well as recruitment of several tyrosine-phosphorylated proteins to IL-12Rβ1 in DCs and Con A blasts. Receptor engagement of DCs as well as Con A blasts by IL-12 resulted in activation of Janus kinase 2 and Tyk2 kinases and Stat3 and Stat4 transcription factors and the association of these proteins to IL-12Rβ1. Stimulation with IL-12 caused a tyrosine phosphorylation and enzymatic activity of a family of mitogen-activated protein kinases, p38mapk. These results suggest that IL-12 acts directly on DCs to induce their functional activation via IL-12Rβ1-mediated signaling events.

Activation of the contact system by filtration of platelet concentrates with a negatively charged white cell‐removal filter and measurement of venous blood bradykinin level in patients who received filtered platelets

BACKGROUND: Several recent reports have described hypotensive transfusion reactions in patients receiving platelet concentrates (PCs) filtered through white cell‐reduction filters. It is well known that a negatively charged surface activates the contact system, consisting of factor XII, prekallikrein, and high‐molecular‐weight kininogen.

Activation of human Vα24NKT cells by α-glycosylceramide in a CD1d-restricted and Vα24TCR-mediated manner

Vα14NK(natural killer) T cells play an important role in controlling tumors or in preventing autoimmunity in the murine system. Vα24NKT cells, the human counterpart of Vα14NKT cells, may contribute to controlling the progression of autoimmune diseases in humans. These findings show the possibility that ligand(s) for these NKT cells can control the above-mentioned pathological conditions. Specific glycolipids such as α-galactosylceramide (α-GalCer) and α-glucosylceramide (α-GlcCer) have been identified as ligand(s) recognized by murine Vα14NKT cells in a CD1d-restricted manner, but it remains unclear whether these glycolipids are ligand(s) for Vα24NKT cells in humans. To determine whether α-glycosylceramide is presented by CD1d molecules in humans, we initially established a Vα24NKT cell line specific for α-glycosylceramide using dendritic cell (DC) like cells from normal peripheral blood mononuclear cells (PBMC) in an autologous mixed leukocyte reaction (auto-MLR) system, and characterized the Vα24NKT cell line. The Vα24NKT cells were CD3+CD4−CD8−Vα24+Vβ11+NKRP1A+ and specifically proliferated in response to α-glycosylceramide in CD1d-restricted and Vα24TCR-mediated manner. The phenotypic and functional similarities between murine Vα14NKT cells and human Vα24NKT cells suggest that Vα24NKT cells may play an important role in controlling tumors or in preventing autoimmunity as observed with Vα14NKT cells.

IgE antibody‐mediated shock reaction caused by topical application of chlorhexidine

A case of an anaphylactic shock following topical application of chlorhexidine preparation is reported. Specific skin‐sensitizing antibodies against chlorhexidine were demonstrated in the serum from the patient by a passive transfer test. IgE antibodies against chlorhexidine were also detected by radioallergosorbent technique (RAST). Paper discs conjugated with chlorhexidine‐HSA (human serum albumin) significantly bound the IgE antibodies. Furthermore, all of the sera from seven other patients with shock reactions following the topical application of chlorhexidine preparation also showed high RAST counts. Both chlorhexidine gluconate and chlorguanide which represents approximately half a molecule of chlorhexidine inhibited the reaction in a dose‐dependent fashion. It is suggested that the shock reactions following topical application of chlorhexidine are mediated by IgE antibodies against chlorhexidine and that chlorhexidine and chlorguanide share the same antigenic determinant.

Current prevalence of HTLV-1 in Japan as determined by screening of blood donors†‡

Human T‐cell leukemia virus type‐1 (HTLV‐1), a major source of adult T‐cell leukemia and related diseases, is endemic to southwestern Japan. Mother‐to‐infant transmission via breast milk is an important route of infection, and establishing programs to prevent such transmission requires exact figures on the HTLV‐1 prevalence rate and the number of carriers. Therefore, the seroprevalence of HTLV‐1 among 1,196,321 Japanese first‐time blood donors from 2006 to 2007 was investigated. A total of 3,787 of such donors were confirmed to be positive for anti‐HTLV‐1 antibody. By applying a fitness curve to the age ranges outside the blood donor age range, the present number of HTLV‐1 carriers covering ages from 0 to 99 years was estimated to be at least 1.08 million in Japan; this value was 10% lower than that reported in 1988. The adjusted overall prevalence rates were estimated to be 0.66% and 1.02% in men and women, respectively. The peak in carrier numbers was found among individuals in their 70s, which is a shift from the previous peak observed in the 1988 database among individuals in their 50s. Carriers were distributed not only in the endemic southwestern region of Japan, but throughout the country, particularly in the greater Tokyo metropolitan area. By applying population projections, it was calculated that the carrier number will decrease by half in the next two decades; however, the carrier population will age over that interval, meaning that the age of patients with adult T‐cell leukemia will also be higher. J. Med. Virol. 84:327–335, 2012.