Search PubMed⌕ Search

Biomedical subjects

K Tamada

Publications and source records attributed to K Tamada.

At least 73 records · Page 4Linked to original sources
PubMed1998

Positive selection of extrathymically developed T cells by self-antigens.

Most T cells develop through the thymus, where they undergo positive and negative selection. Some peripheral T cells are known to develop in the absence of thymus, but there is insufficient information about their selection. To analyze the selection of extrathymically developed T cells, we reconstituted thymectomized male or female recipient mice with bone marrow cells of mice transgenic for male H-Y antigen-specific T cell receptor (TCR). It was revealed that the T cells bearing self-antigen-specific TCR were not deleted in thymectomized male recipients. More importantly, the absence of H-Y antigen-specific T cells in thymectomized female recipients suggests positive selection of extrathymically developed T cells by the self-antigen. The extrathymically developed T cells in male mice expressed interleukin (IL)-2 receptor beta chain (IL-2Rbeta) and intermediate levels of CD3 (CD3(int)) but were natural killer cell (NK)1.1(-). They rapidly produced interferon gamma but not IL-4 after TCR cross-linking. Furthermore, a similar pattern of cytokine production was observed in CD3(int)IL-2Rbeta+NK1.1(-) cells in normal mice which have been shown to develop extrathymically. These results suggest that extrathymically developed CD3(int)IL-2Rbeta+NK1. 1(-) cells in normal mice are also positively selected by self-antigens.

Animals↗
PubMed1998

IL-4-producing NK1.1+ T cells are resistant to glucocorticoid-induced apoptosis: implications for the Th1/Th2 balance.

To elucidate the mechanisms by which glucocorticoids promote Th2-type responses, we investigated the influence of dexamethasone (DEX) on both cytokine production and viability of NK1.1+ T cells. The in vivo administration of DEX enhanced the IL-4 production of spleen cells and liver mononuclear cells in wild-type mice, but not in beta2m-deficient mice. DEX reduced the cellularity of conventional T cells, but not that of NK1.1+ T cells, in both spleen and liver, suggesting an increased proportion of NK1.1+ T cells. Moreover, the proportion of IL-4-producing NK.1 + T cells increased in the DEX-injected mice. These results suggest that DEX induced IL-4 production through the preferential survival of IL-4-producing NKI.1+ T cells. In investigating the reason for the preferential survival of NK1.1+ T cells, we found that NK1.1+ T cells were resistant to DEX-induced apoptosis and expressed a higher level of intracellular Bcl-2 compared with conventional NKI.1- T cells. In addition, splenic and hepatic NK1.1+ T cells were resistant to radiation-induced apoptosis. Collectively, our findings revealed an important role for NK1.1+ T cells in the regulation of Th1/Th2 balance by glucocorticoids and their possible functions under various apoptotic stimuli.

Animals↗
PubMed1998

Role of the endogenous production of interleukin 12 in immunotherapy.

Previous studies demonstrated that injecting mice with the cytokine interleukin 12 (IL-12) could significantly suppress the growth of a number of tumors, including murine B16 melanoma. In this report, the persistence of the antitumor effects of IL-12 is investigated. The i.p. injection of IL-12 (0.1 microg) on days 14, 16, 18, 20, and 22 was found to significantly suppress the growth of s.c. inoculated B16 melanoma for up to 2 weeks after the last injection of IL-12. Interestingly, the IL-12 serum level 4 days after the last injection of IL-12 was significantly elevated in tumor-bearing mice compared with that of IL-12-treated normal mice. The in vivo depletion of either CD4+ or CD8+ T cells abrogated the antitumor activity of IL-12 and diminished the apparent autocrine stimulation of IL-12 release seen after IL-12 treatment. Resection of the tumor-draining lymph nodes (LNs) but not of the spleen abrogated the antitumor effect of IL-12 treatment as well as the elevation of serum IL-12. Expression of mRNA encoding IL-12 as well as CD40 ligand (CD40L) was detected in the tumor-draining LNs but not in the spleen of tumor-bearing mice after IL-12 treatment. Furthermore, the antitumor activity observed after IL-12 treatment was diminished by the in vivo administration of either anti-IL-12 or anti-CD40L monoclonal antibodies. Collectively, these results suggest that the endogenous production of IL-12 resulting from the CD40-CD40L interaction between antigen-presenting cells and CD4+ T cells in the tumor-draining LNs may play a role in the persistence of the antitumor effects seen after IL-12 treatment.

Animals↗
PubMed1998

Systemic administration of interleukin-12 can restore the anti-tumor potential of B16 melanoma-draining lymph node cells impaired at a late tumor-bearing state.

We investigated the effect of the systemic administration of interleukin (IL)-12 on the anti-tumor potential of tumor-draining lymph nodes (LNs). Tumor-draining LN cells on day 10 after s.c. inoculation of B16 melanoma showed a significant anti-tumor effect against established pulmonary metastases after in vitro expansion, whereas those on either day 20 or 30 exhibited an impaired anti-tumor potential. However, i.p. injections of IL-12 (0.5 microg) on days 18, 20 and 22 significantly increased the total number of tumor-draining LN cells on day 24 and, furthermore, restored their anti-tumor potential after in vitro expansion. In addition, i.p. injection of IL-12 (0.1 microg) on days 20, 22, 24, 26 and 28 significantly suppressed the growth of s.c.-inoculated B16 melanoma and finally cured the tumors in 6 of 12 mice (50%), whereas dissection of the tumor-draining LNs on day 18, prior to the IL-12 treatment, decreased both the IL-12-induced anti-tumor effect and the percentage of cured mice (8.3%). Cured mice acquired a specific protective immunity. Collectively, our results indicate that the systemic administration of IL-12 can restore the immunotherapeutic potential of tumor-draining LNs, which was impaired at the late tumor-bearing state, and that the IL-12-induced systemic anti-tumor activity is preceded by the restoration of an anti-tumor response in tumor-draining LNs.

Animals↗
PubMed1998

Early-appearing tumor-infiltrating natural killer cells play an important role in the nitric oxide production of tumor-associated macrophages through their interferon production.

Both natural killer (NK) cells and macrophages are thought to be the main effectors responsible for early antitumor defense. In this study, we investigated the role of tumor-infiltrating NK cells in initiating nitric oxide (NO) production by tumor-associated macrophages (TAM). The in vivo depletion of NK cells prior to the i.p. inoculation of melanoma cells resulted in a significant decrease in the NO production of the TAM prepared from the peritoneal exudate cells (PEC). Such prior NK cell depletion also decreased the ability of TAM to show any antitumor activity in vitro. The addition of NG-monomethyl-L-arginine (Me-L-Arg) to the culture partially inhibited the ability of TAM to suppress the proliferation of melanoma cells and also decreased their cytolytic activity against melanoma cells. These results suggest that the TAM exhibited both cytostatic and cytolytic activities through their NO production. In an in vivo assay, the administration of Me-L-Arg permitted the more rapid growth of i.p. inoculated melanoma cells compared with the control. On the other hand, the decreased NO production of TAM, resulting from the prior NK cell depletion, was restored by the i.p. administration of interferon gamma (IFN gamma). In addition, the in vivo administration of anti-IFN gamma mAb into mice inoculated i.p. with melanoma cells also significantly decreased the NO production of TAM in peritoneal exudate cells. Furthermore, the tumor-infiltrating NK cells produced a considerable level of IFN gamma. Overall, these results indicate that early-appearing tumor-infiltrating NK cells play an important role in the NO production of TAM through their IFN gamma production.

Animals↗
PubMed1998

Antitumor vaccination effect of dendritic cells can be augmented by locally utilizing Th1-type cytokines from OK432-reactive CD4+ T cells.

In order to enhance the antitumor vaccination effect of dendritic cells (DC) pulsed with class I tumor peptide, we tried to utilize the local cytokine help of CD4+ T cells reactive to a streptococcal preparation OK432. DC were prepared from murine bone marrow cells by culture with both granulocyte/macrophage-colony-stimulating factor and interleukin(IL)-4. The peritumoral injections of OK432 induced OK432-reactive CD4+ T cells in the draining lymph nodes, and their in vitro production of interferon gamma was thus significantly enhanced by restimulation with OK432-pulsed DC. In addition, anti-P815 mastocytoma cytotoxic T lymphocytes were generated from the in vivo OK432-treated P815-draining lymph node cells only when the lymph node cells were restimulated in vitro with the DC pulsed with both P1A peptide and OK432. Moreover, the peritumoral injections of OK432 and the subsequent vaccination of the DC, pulsed with both OK432 and P1A peptide, significantly suppressed the growth of s.c. inoculated P815. Interestingly, a significant level of IL-12 was detected in the coculture supernatant of both OK432-pulsed DC and OK432-reactive CD4+ T cells. Collectively, our results suggest that the antitumor vaccination effect of DC pulsed with class I tumor peptide could thus be effectively augmented by locally utilizing the Th1-type cytokines from OK432-reactive CD4+ T cells.

Animals↗
PubMed1998

Characterization of B16 melanoma-specific cytotoxic T lymphocytes.

A B16 melanoma-specific CD8+ T cell line (AB1) was established from the spleen cells of C57BL/6 mice cured of B16 melanoma with interleukin (IL)-12 treatment. The AB1 line exclusively used T cell receptor Vbeta11. The AB1 cells exhibited a cytolytic activity against both syngeneic B16 melanoma and allogeneic P815 mastocytoma, whereas a cold inhibition assay revealed specificity of the AB1 cells against B16 melanoma. Their lostability to kill a class I loss variant of B16 melanoma was restored by the transfection of H-2Kb gene. In addition, their interferon (IFN)-gamma production was significantly suppressed by the addition of anti-H-2Kb monoclonal antibody, and RT-PCR analysis showed that the AB1 line expressed the mRNA encoding IFN-gamma, but not IL-4 or IL-10. The experiment using synthetic peptides of tyrosinase-related protein-2 (TRP-2) revealed that the AB1 cells could recognize TRP-2(181-188) peptide. Moreover, the AB1 cells showed an in vivo antitumor effect against established pulmonary metastases of B16 melanoma. Overall, these results indicate that the Tc1-type Vbeta11+ AB1 cells exert an antitumor activity against syngeneic B16 melanoma through recognition of TRP-2(181-188) peptide in an H-2Kb-restricted manner.

Animals↗
PubMed1998

Characterization of biliary strictures using intraductal ultrasonography: comparison with percutaneous cholangioscopic biopsy.

BACKGROUND: We determined the accuracy of intraductal ultrasonography (IDUS) in distinguishing between bile duct cancer and benign bile duct disease. METHODS: Patients (n=42) who required bile duct biopsy using percutaneous transhepatic cholangioscopy (PTCS) to evaluate bile duct strictures or filling defects were studied. A thin-caliber ultrasonic probe (2.0 mm diameter and 20 MHz frequency) was inserted into the bile duct, and its images were prospectively reviewed before PTCS. RESULTS: Disruption of the bile duct wall structure, seen on IDUS, was associated with malignancy in 25 of 26 patients. When IDUS demonstrated a lesion with normal bile duct structure, six of nine patients were found to have no malignancy. IDUS demonstrated no intraductal lesion in seven patients, and bile duct biopsy also did not indicate cancer in any of these patients. The accuracy, sensitivity, and specificity of IDUS for diagnosing bile duct cancer were 76%, 89%, and 50%, respectively. When used in tandem with IDUS, the sensitivity of bile cytology (64%) and PTCS (93%) improved to 96% and 100%, respectively. CONCLUSIONS: The accuracy of IDUS for diagnosing bile duct cancer was less than that of PTCS (95%). However, the sensitivity for bile cytology, or bile duct biopsy improved when performed in combination with IDUS.

Adult↗
PubMed1998

Influence of biliary drainage catheter on bile duct wall thickness as measured by intraductal ultrasonography.

OBJECTIVE: To determine the influence of biliary drainage catheter placement on bile duct wall thickness, we performed intraductal ultrasonography (IDUS) in patients before and after biliary drainage. METHODS: Patients underwent IDUS before and after either short-term (n = 9, 6 to 8 days) or long-term (n = 9, 14 to 35 days) biliary drainage using a thin (2.0 mm diameter), 20 MHz probe inserted by means of a transpapillary route or a percutaneous tract. The bile duct wall thickness (mean +/- standard deviation) was retrospectively measured at the upper portion of the common hepatic duct. RESULTS: The bile duct wall thickness increased from 0.8+/-0.4 mm (predrainage) to 2.0+/-1.6 mm (post-drainage) in the long-term group (p < 0.001) but was not significantly increased in the short-term group. CONCLUSIONS: The bile duct wall thickness as measured on IDUS appears to be increased after placement of biliary drainage catheters.

Aged↗
PubMed1998

Vaccination with activated B cells pulsed with tumor-lysates can induce tumor-specific CD4+ T cells in vivo.

Activated B cells, pulsed with tumor-lysates, were examined for their potential to induce tumor-specific CD4+ T cells in vivo, MH2 cells, which are CD4+ T cells and can also recognize purified protein derivative from mycobacterium tuberculosis (PPD), showed a proliferative response in the presence of both syngeneic activated B cells and PPD in a major histocompatibility complex class II-restricted manner. For B cells to function as efficient antigen presenting cells, they need to be activated. Both irradiation and several inhibitors for antigen-processing were observed to block the antigen-presenting ability of activated B cells. Based in these findings, the possibility of anti-tumor vaccination with activated B cells was thus investigated. The spleen cells from mice, which were immunized with activated B cells pulsed with B16 melanoma-lysates, produced a higher level of interferon (IFN)-gamma than those from mice, which were immunized with either non-pulsed activated B cells or the tumor-lysates alone, after in vitro restimulation. This IFN-gamma production was also dependent on the CD4+ T cells. Moreover, the splenic CD4+ T cells in such mice were suggested to increase their ability to generate B16 melanoma-specific cytotoxic T lymphocytes after in vitro restimulation. Even more importantly, immunization with B16 melanoma lysate-pulsed activated B cells elicited a protective immunity against B16 melanoma at rechallenge. Collectively, these results indicate that an anti-tumor effect could be induced by immunization with activated B cells, pulsed with the tumor-lysates, by eliciting tumor-specific IFN-gamma producing CD4+ T cells in vivo.

Animals↗
PubMed1998

Involvement of both donor cytotoxic T lymphocytes and host NK1.1+ T cells in the thymic atrophy of mice suffering from acute graft-versus-host disease.

It has been reported that a dramatic decrease in the number of thymocytes (thymic atrophy) in mice suffering from acute graft-versus-host disease (GVHD) is ascribed to glucocorticoids. In this study, we examined the possibility that cellular immune responses may thus be involved in thymic atrophy. In contrast to chronic GVHD mice, acute GVHD (C57BL/6 X DBA/2) F1 (BDF1) hybrid mice, which were injected intravenously with both spleen and lymph node cells from C57BL/6 mice, showed a dramatic decrease in the number of CD4 CD8 double-positive thymocytes 2 or 3 weeks after the induction of GVHD. A flow cytometric analysis revealed the donor-derived T cells with either CD4 or CD8 molecules to infiltrate the thymus of the mice undergoing acute GVHD for 10 days. In a cytolytic assay, such thymus-containing cells exhibited a cytolytic activity specific to the host cells. In addition, anti-H-2d cytolytic T cells showed a high level of cytolytic activity against BDF1 (H-2bXd) thymocytes, whereas they also showed a low level of cytolytic activity against C57BL/6 (H-2b) thymocytes, thus suggesting that the thymus-infiltrating donor-derived T cells killed the host thymocytes through both anti-H-2d-specific and non-specific mechanisms. Interestingly, a flow cytometric analysis revealed both the percentage and the absolute cell number of host-derived NK1.1+ CD3+ cells to increase in the thymus of mice suffering from acute GVHD for 10 days. In addition, they also showed the cytolytic activity against YAC-1 cells and the mRNA expression of interleukin-12 (IL-12) in the thymus to be also significantly augmented on day 7 after the induction of acute GVHD. Collectively, our results indicate that the cellular immune responses such as donor cytotoxic T lymphocytes and host NK1.1+ T cells are therefore involved in the thymic atrophy of mice suffering from acute GVHD.

Acute Disease↗
PubMed1997

Immunosuppressive activity of cloned natural killer (NK1.1+) T cells established from murine tumor-infiltrating lymphocytes.

To elucidate the role of NK1.1+ T cells in the antitumor immune response, we established cloned NK1.1+ T cell lines from tumor-infiltrating lymphocytes (TIL) of B16 melanoma, and examined their mode of action in generating antitumor effector T cells both in vitro and in vivo. An NK1.1+ T cell clone (TM4.2) was phenotypically CD3+ TCR-alphabeta+ CD4- CD8- NK1.1+, and CD28+. The TM4.2 cells suppressed the in vitro generation of anti-B16 melanoma CTLs, but not the effector function of CTLs. The results using a transwell membrane suggested that their suppressive activity was mediated by both soluble factors and a direct cell to cell interaction. As for the soluble factors, the suppressive activity of the culture supernatant of TM4.2 cells was neutralized by anti-TGF-beta mAb, and the TM4.2 cells actually produced a considerable amount of TGF-beta. On the other hand, the TM4.2 cells showed a high level of cytolytic activity against B cell blasts and CD80-transfected P815, and such cytolytic activity was reduced by the addition of anti-CD80 mAb. In addition, NK1.1+ T cells in the freshly isolated TIL were revealed to express CD28. Furthermore, the TM4.2 cells suppressed the in vitro generation of anti-allo CTLs irrespective of the MHC haplotype. Finally, the TM4.2 cells suppressed the in vivo antitumor immune response. Collectively, these findings demonstrate that NK1.1+ T cells in TIL show immunosuppressive activity in the antitumor immune response through the production of TGF-beta and the preferential cytolysis of B7-expressing cells.

Animals↗
PubMed1997

Local injection of OK432 can augment the TH1-type T-cell response in tumor-draining lymph node cells and increase their immunotherapeutical potential.

The effect of local injections with streptococcal preparation OK432 on the therapeutical potential of tumor-draining lymph node (LN) cells was investigated in mice. Peritumoral injections with OK432 on days 2, 4, 6, 8 and 10 showed no effect on the in vivo growth of s.c. inoculated B16F10 melanoma. The B16F10-draining OK432-treated LN cells, however, showed a high level of anti-B16F10 cytolytic activity after an in vitro culture first with both anti-CD3 monoclonal antibody (MAb) and activated B cell blasts, and subsequently with interleukin (IL)-2 without in vitro restimulation. Such in vitro expanded LN cells showed a remarkable antitumor effect against pulmonary metastasis of B16F10 melanoma, even without the concurrent administration of IL-2. In addition, the therapeutical protocol was also found to be moderately effective against poorly immunogenic MCA fibrosarcoma, and the in vivo antitumor effect was specific to the tumor from which the LNs were harvested. Interestingly, 2 kinds of comparative analyses of the cytokines revealed that the B16F10-bearing state induced the draining LN cells to develop a Th2-type response. However, the OK432 treatment was able to effectively augment their Th1-type response. Collectively, our results suggest that peritumoral injections with OK432 significantly increased the therapeutical potential of the tumor-draining LN cells by augmenting their Th1-type response.

Animals↗
PubMed1997

Oral administration of PSK can improve the impaired anti-tumor CD4+ T-cell response in gut-associated lymphoid tissue (GALT) of specific-pathogen-free mice.

We investigated both the effect and the mechanism of oral (p.o.) administration of PSK, a protein-bound polysaccharide derived from Basidiomycetes, on the anti-tumor T-cell response in gut-associated lymphoid tissue (GALT). The p.o. administration of PSK significantly suppressed the growth of colon 26 carcinoma (C-26) inoculated into the subserosal space of the cecum (i.c.), and augmented the tumor-neutralizing activity of the draining mesenteric lymph node (LN) cells. PSK treatment also significantly decreased the levels of immunosuppressive factors such as plasma transforming growth factor (TGF)-beta in the i.c. C-26-inoculated mice. We also evaluated the improving effect of PSK on the anti-tumor T-cell response in GALT by utilizing B7-transfected P815 mastocytoma (B7/P815). The PSK treatment promoted the rejection of i.c.-inoculated B7/P815 and restored the CD4+ T-cell-dependent proliferative response of the draining mesenteric LN cells against in vitro restimulation. Furthermore, the treatment also decreased the TGF-beta production but increased the IFN-gamma production of these cells. The p.o. administration of PSK, however, showed no effect in the CD8+ T-cell-dependent cytolytic activity of the draining mesenteric LN cells after in vitro restimulation. Overall, these results indicate that the p.o. administration of PSK can improve the impaired anti-tumor CD4+ T-cell response in GALT, mainly through a suppression of TGF-beta production and a restoration of IFN-gamma production.

Administration, Oral↗
PubMed1997

Diagnosing extrahepatic bile duct stones using intraductal ultrasonography: a case series.

BACKGROUND AND STUDY AIMS: Intraductal ultrasonography (IDUS), a new ultrasonographic diagnostic procedure, was used to assess the presence of extrahepatic bile duct stones. PATIENTS AND METHODS: The IDUS apparatus consisted of a 6-French high-frequency (20 MHz) probe. Prior to clinical application, in-vitro studies were conducted in a water tank. Clinically, IDUS was successful in 31 patients after endoscopic retrograde cholangiography. Interpretations of IDUS images were evaluated in comparison with cholangiographic and fluoroscopic findings. RESULTS: Experimental testing demonstrated that stones or fragments were typically visualized as strong, high-echo images with acoustic shadowing; air bubbles were seen as fan-shaped high-echo areas or comet-shaped high-echo areas; and sludge was visualized as soft, easily changing, high-echo structures. Extrahepatic bile duct stones were visualized by IDUS in 30 of 31 patients (96.8%), while fluoroscopy and cholangiography identified 19 (61.3%) and 25 (80.6%), respectively. Accurate differentiation between stones and air bubbles was also possible. CONCLUSION: IDUS could be a useful modality in the diagnosis of extrahepatic bile duct stones.

Adult↗
PubMed1997

Limitations of intraductal ultrasonography in differentiating between bile duct cancer in stage T1 and stage T2: in-vitro and in-vivo studies.

BACKGROUND AND STUDY AIMS: We investigated whether intraductal ultrasonography (IDUS) could distinguish between stage T1 and T2 bile duct cancer. MATERIALS AND METHODS: In-vitro study. Resected bile duct specimens (n = 8) were immersed in a water tank and were pierced with straight pins to clarify the normal layer structure. Ultrasonosgraphic images (20MHz) of the positions of pin echoes were compared to the positions of pin holes as seen on histologic analysis of the specimens. In-vivo study. A thin-caliber high-frequency (6 Fr, 20 MHz) ultrasonic probe was inserted into the bile duct via a transhepatic route or a transpapillary route in 26 patients with bile duct cancer who underwent surgical resection. RESULTS: In-vitro study. The inner hypoechoic layer on the IDUS image corresponded not only to the fibromuscular layer but also to a part of fibrous layer of the perimuscular loose connective tissue on histologic analysis, especially in the cases with moderate to severe bile duct wall fibrosis. The outer hyperechoic layer corresponded to the subserosal fat tissue. In-vivo study. In four of six patients with tumor limited to the inside hypoechoic layer on IDUS images, the histologic findings showed tumor invasion to the fibrous layer of the perimuscular loose connective tissue. Due to this limitation, accuracy of IDUS in T-staging was only 20/26 (77 %). CONCLUSIONS: IDUS cannot reliably distinguish bile duct cancer in stage T1 from that in stage T2.

Adult↗
PubMed1997

The role of endoscopic balloon sphincteroplasty in patients with gallbladder and bile duct stones.

We clarified the significance of endoscopic balloon sphincteroplasty (EBS) in the therapeutic treatment of biliary tract stones in the present era of laparoscopic cholecystectomy (LC). Patients with cholecysto-choledocholithiasis (n = 33) were treated by EBS. After endoscopic retrograde cholangiography (ERC), a balloon catheter (8 mm in diameter and 3 cm in width) was inserted into the bile duct using a guidewire, and positioned at the sphincter of Oddi. After inflating the balloon catheter, bile duct stones were removed by mechanical lithotripsy, a basket catheter, or a balloon catheter. In all patients, bile duct stones were removed by EBS without endoscopic sphincterotomy. No complication occurred except for 2 cases of mild pancreatitis, which was resolved within 48 hours. Twenty-four patients underwent LC before or after EBS. The remaining 9 patients did not undergo LC due to a poor-risk status for general anesthesia. None of them, however, experienced cholecystitis or colicky attacks after EBS. The combination of EBS and LC is an excellent method for treating cholecysto-choledocholithiasis.

Aged↗