Biomedical subjects

K Ami

Publications and source records attributed to K Ami.

14 recordsLinked to original sources

PubMed2002

Activation of human T cells with NK cell markers by staphylococcal enterotoxin A via IL-12 but not via IL-18.

We have reported recently that mouse liver NK cells and NK1 x 1+ T cells were activated by bacterial superantigens via the IL-12 production from Kupffer cells. In the present study, we examined the effect of staphyloccoccal enterotoxin A (SEA) on human T cells with NK cell markers, CD56 or CD57 (NK-type T cells). After stimulating peripheral blood mononuclear cells (PBMC) with SEA, PBMC produced a large amount of IFN- and acquired a potent antitumour cytotoxicity. The in vitro depletion of either CD56+ TCR NK cells, CD56+ T cells or 57+ T cells from PBMC significantly inhibited the IFN- production from PBMC. When purified NK-type T cells, NK cells and regular T cells were cultured with monocytes and SEA they all produced IFN-, while the IFN- amounts produced by both NK-type T cells were greater than those produced by NK cells. NK cells as well as CD56+ T cells showed cytotoxicity against NK-sensitive K562 cells, whereas both NK-type T cells showed a more potent cytotoxicity against NK-resistant Raji cells than did NK cells. The IFN- production from each population as well as from whole PBMC was greatly inhibited by anti-IL-12 antibody but not by anti-IL-18 antibody. The antitumour cytotoxicity of whole PBMC was also significantly inhibited by anti-IL-12 antibody while the SEA-induced proliferation of PBMC was not affected by anti-IL-12 antibody. Furthermore, SEA-activated NK-type T cells as well as NK cells showed cytotoxicities against vascular endothelial cells. Our findings suggest that human NK-type T cells are thus involved in bacterial superantigen-induced immune response.

Biomarkers↗

PubMed2001

The mechanism of a defective IFN-gamma response to bacterial toxins in an atopic dermatitis model, NC/Nga mice, and the therapeutic effect of IFN-gamma, IL-12, or IL-18 on dermatitis.

NC/Nga (NC) mice raised under conventional conditions (Conv. NC mice) spontaneously develop dermatitis similar to human atopic dermatitis, whereas NC mice raised under the specific pathogen-free conditions do not develop dermatitis. In the present study, we show that the representative Th1 cytokine, IFN-gamma levels in the sera of NC mice, injected with either staphylococcal enterotoxin B or endotoxin (LPS), to be severalfold lower than those of normal mice. The low IFN-gamma response to staphylococcal enterotoxin B was correlated to the lack of regular Vbeta8(+) T cells and Vbeta8(+) NK T cells, and the low IFN-gamma response to LPS was correlated to an impaired IL-18 production of macrophages. The CD3-stimulated IL-4 production from liver and spleen T cells from Conv. NC mice in vitro was greatly augmented. The serum IL-4 levels of untreated Conv. NC mice also were higher than those of normal mice and specific pathogen-free NC mice. Treatment of Conv. NC mice either with IFN-gamma, IL-12, or IL-18 twice a week from 4 wk of age substantially inhibited the elevation of the serum IgE levels, serum IL-4 levels, and dermatitis, and IL-12 or IL-18 treatment also reduced the in vitro IL-4 production from CD3-stimulated liver T cells. The systemic deficiency in the Th1 response to bacterial stimulation thus leads to a Th2-dominant state and may induce an abnormal cellular immune response in the skin accompanied with an overproduction of IgE and a susceptibility to dermatitis in NC mice.

Adjuvants, Immunologic↗

PubMed2001

Systematic characterization of human CD8+ T cells with natural killer cell markers in comparison with natural killer cells and normal CD8+ T cells.

We investigated the function of CD56+ CD8+ T cells (CD56+ T cells) and CD56- CD57+ CD8+ T cells (CD57+ T cells; natural killer (NK)-type T cells) and compared them with those of normal CD56- CD57- CD8+ T cells (CD8+ T cells) and CD56+ NK cells from healthy volunteers. After the stimulation with immobilized anti-CD3 antibodies, both NK-type T cells produced much larger amounts of interferon-gamma (IFN-gamma) than CD8+ T cells. Both NK-type T cells also acquired a more potent cytotoxicity against NK-sensitive K562 cells than CD8+ T cells while only CD56+ T cells showed a potent cytotoxicity against NK-resistant Raji cells. After the stimulation with a combination of interleukin (IL)-2, IL-12 and IL-15, the IFN-gamma amounts produced were NK cells > or = CD56+ T cells > or = CD57+ T cells > CD8+ T cells. The cytotoxicities against K562 cells were NK cells > CD56+ T cells > or = CD57+ T cells > CD8+ T cells while cytotoxicities against Raji cells were CD56+ T cells > CD57+ T cells > or = CD8+ T cells > or = NK cells. However, the CD3-stimulated proliferation of both NK-type T cells was smaller than that of CD8+ T cells partly because NK-type T cells were susceptible to apoptosis. In addition to NK cells, NK-type T cells but not CD8+ T cells stimulated with cytokines, expressed cytoplasmic perforin and granzyme B. Furthermore, CD3-stimulated IFN-gamma production from peripheral blood mononuclear cells (PBMC) correlated with the proportions of CD57+ T cells in PBMC from donors. Our findings suggest that NK-type T cells play an important role in the T helper 1 responses and the immunological changes associated with ageing.

Adult↗

PubMed2000

Mouse CD8+ CD122+ T cells with intermediate TCR increasing with age provide a source of early IFN-gamma production.

Although CD8+ IL-2Rbeta (CD122)+ T cells with intermediate TCR reportedly develop extrathymically, their functions still remain largely unknown. In the present study, we characterized the function of CD8+ CD122+ T cells with intermediate TCR of C57BL/6 mice. The proportion of CD8+ CD122+ T cells in splenocytes gradually increased with age, whereas CD8+ IL-2Rbeta-negative or -low (CD122-) T cells conversely decreased. The IFN-gamma production from splenocytes stimulated with immobilized anti-CD3 Ab in vitro increased with age, whereas the IL-4 production decreased. When sorted CD8+ CD122+ T cells were stimulated in vitro by the anti-CD3 Ab, they promptly produced a much larger amount of IFN-gamma than did CD8+ CD122- T cells or CD4+ T cells, whereas only CD4+ T cells produced IL-4. The depletion of CD8+ CD122+ T cells from whole splenocytes greatly decreased the CD3-stimulated IFN-gamma production and increased the IL-4 production, whereas the addition of sorted CD8+ CD122+ T cells to CD8+ CD122+ T cell-depleted splenocytes restored the IFN-gamma production and partially decreased IL-4 production. It is of interest that CD8+ CD122+ T cells stimulated CD4+ T cells to produce IFN-gamma. The CD3-stimulated IFN-gamma production from each T cell subset was augmented by macrophages. Furthermore, CD3-stimulated CD8+ CD122+ T cells produced an even greater amount of IFN-gamma than did liver NK1.1+ T cells and also showed antitumor cytotoxicity. These results show that CD8+ CD122+ T cells may thus be an important source of early IFN-gamma production and are suggested to be involved in the immunological changes with aging.

Aging↗

PubMed2000

A simple technique of using novel thread-holding and knot-pushing forceps for extracorporeal knot-tying.

We designed some novel knot-pushing forceps for extracorporeal knot-tying and describe herein our simple technique of utilizing them. These forceps are modified only by a single 1-mm hole between their jaws, which hold a thread and push the knot toward the ligating tissue. The application of this simple device was handled well by surgeons beginning to perform advanced endoscopic surgery. The simple modification explained in this report seems applicable to most of the forceps currently used.

Endoscopy↗

PubMed2000

Decrease of CD56(+)T cells and natural killer cells in cirrhotic livers with hepatitis C may be involved in their susceptibility to hepatocellular carcinoma.

CD56(+)T cells and CD56(+)natural killer (NK) cells are abundant in the human liver. The aim of this study was the further characterization of these cells in the liver with or without hepatitis C virus (HCV) infection. Liver mononuclear cells (MNC) were isolated from liver specimens obtained from the patients during abdominal surgery. In addition to a flow cytometric analysis, liver MNC and PBMC were cultured with the immobilized anti-CD3 Ab, IL-2, or a combination of IL-2 and IL-12 and their IFN-gamma production and the antitumor cytotoxicity were assessed. The liver MNC of HCV (-) patients contained 20% CD56(+)T cells whereas the same proportions decreased to 11% in chronic hepatitis livers and to 5% in cirrhotic livers. The proportion of NK cells also decreased in the cirrhotic livers. On the other hand, the populations of these cells in PBMC did not significantly differ among patient groups. The IFN-gamma production and the cytotoxicity against K562 cells, Raji cells, and a hepatocellular carcinoma, HuH-7 cells, greatly decreased in the cirrhotic liver MNC. In contrast, the cytotoxicity in PBMC did not significantly differ among the patient groups and was lower than that in the liver MNC of HCV (-) patients. CD56(+)T cells and NK cells but not regular T cells purified from liver MNC cultured with cytokines showed potent cytotoxicities against HuH-7 cells. These results suggest that a decreased number of CD56(+)T cells and NK cells in cirrhotic livers may be related to their susceptibility to hepatocellular carcinoma.

Aged↗

PubMed2000

A novel method of virtual histopathology using laser-scanning confocal microscopy in-vitro with untreated fresh specimens from the gastrointestinal mucosa.

BACKGROUND AND STUDY AIMS: Histopathological examination for superficial gastrointestinal lesions has been mainly based upon the light microscopic examination of thin-slice specimens with hematoxylin and eosin (H&E) staining. However, it takes at least a couple of days to create a slide-glass for microscopic study. In order to obtain immediate microscopic images for untreated specimens, the authors used laser-scanning confocal microscopy (LCM) to study fresh samples of gastrointestinal mucosa. MATERIALS AND METHODS: Fresh untreated mucosal specimens from the esophagus, stomach, and colon, obtained by endoscopic pinch biopsy, polypectomy, or endoscopic mucosal resection (EMR), were fixed in normal saline and examined by LCM collecting the reflective light of a 488-nm wavelength argon laser beam. Findings from the LCM image were compared with those of conventional H&E staining in all specimens. For objective evaluation of the similarity of both pictures, the nucleus-to-cytoplasm ratio (N/C) of normal mucosa and that of cancer of the esophagus were calculated and statistically analyzed. The overall diagnostic accuracy for cancer was evaluated. RESULTS: The average scanning time to obtain the LCM image of a specimen was 1.6 seconds. The LCM images acquired corresponded well to the conventional H&E light microscopic images in the esophagus, stomach, and colon. Cell wall, nucleus, cytoplasm, and tissue structural elements were simultaneously visualized by LCM scanning. A difference in N/C ratios between normal mucosa and cancer in the esophagus was statistically apparent when Welch's test (P=0.05) was applied. The overall diagnostic accuracy of the LCM study for cancer was 89.7%. CONCLUSIONS: This novel method enables us to obtain an immediate serial virtual microscopic section through a fresh specimen, which has not actually been cut, although the resolution of the image obtained is still limited. These early results encourage us to develop imaging relevant to conventional histopathology alongside the development of LCM technology in the near future. We should aim at the in vivo application of LCM coupled to probes which can be introduced through the working channel of endoscopes.

Colon↗

PubMed1998

[A case of hepatic metastasis of rectal cancer with familial adenomatous polyposis treated by transarterial administration of low-dose leucovorin and 5-FU].

A 37-year-old man was diagnosed as having a rectal cancer with familial adenomatous polyposis, with the mutation of APC gene, and gastric polyposis, hypertrophy of the retinal pigment epithelium and a lipoma of the left arm. The patient underwent a total colectomy for the rectal cancer and a partial resection of the liver for metastasis (S3) which was detected on laparotomy, followed by cannulation in the hepatic artery. After the operation, 5-FU alone and low doses of CDDP and 5-FU were administered, but the level of serum CEA elevated and CT scanning showed multiple liver metastases. Then, low doses of leucovorin (30 mg/body bolus) and 5-FU (500 mg/body/h) were injected through an injection port every week. After 6 months, the level of serum CEA reduced and CT scanning showed minor response (about 30% on the decrease rate), without side effects, including diarrhea, stomatitis and bone marrow suppression.

Adenomatous Polyposis Coli↗

PubMed1979