Toyoo Nitta

Experimental studies on morphological changes of microcirculation of DMN-induced liver cirrhosis after normothermic ischemia with charge-coupled device microscope.

Aim:  The purpose of the present experiment was to find indices for intraoperative ischemic‐reperfusion injury in the cirrhotic liver.

Specific CTL activity of CD8+ TCR Vβ14+ T cell in mouse 2, 4, 6-trinitrobenzene sulfonic acid-induced colitis

We analyzed the functional role of CD8+ T-cell receptor (TCR) Vβ14+ T cells, which increased specifically in the lamina propria in 2,4,6-trinitrobenzene sulfonic acid (TNBS) -induced colitis. Cytotoxic activity and cytokine production in CD8+ TCR Vβ14+ T-cell clones were analyzed by 51Cr release assay and enzyme-linked immunosorbent assay, respectively. Cell transfer studies using these clones were performed. Established T-cell clones showed specific cytotoxic activity against TNBS-conjugated self spleen cells, and this cytotoxicity was completely inhibited by anti-TCR Vβ14 monoclonal antibody. These clones produced interferon (IFN) - γ in their culture supernatant, but neither interleukin (IL) - 2 nor IL-4. Histological findings of the colon in mice, which received clone transfer after enema with suboptimal doses of TNBS, showed massive colitis. Our results indicate that CD8+ TCR Vβ14+ T cells had a cytotoxic T-lymphocyte function induced by Th-1 T-cell response and played a pathogenic role in the development of TNBS-induced colitis.

Helper T-cell type 1 or type 2 function of xeno-MHC-restricted T-cell clones in a direct xenoantigen recognition.

There have been several reports that xeno-MHC-restricted T-cells have a cytotoxic function through a direct xenoantigen recognition, but yet no report that they have a helper function. Previously we showed that both xeno-MHC-restricted CD4(+) and CD8(+) T-cells recognized xenoantigens directly in a mouse anti-rat combination. In this study, we investigated whether or not xeno-MHC-restricted T-cells had a helper function. Mouse T-cell clones recognizing rat antigens directly were derived from T-cell lines using the limiting dilution method. Phenotype, cytotoxic activity and cytokine production of these clones were analyzed by flow cytometry, 51Cr release assay and ELISA, respectively. Rat-MHC class I-restricted mouse CD8(+) T-cell clones showed a specific cytotoxic activity against rat antigens. One CD4(+) clone produced IL-4 and IL-10, and the other CD4(+) clone produced not T-helper (Th) 2 cytokine but TNF-alpha. Our results suggested that xeno-MHC class I-restricted CD8(+) T-cells should have a cytotoxic function, and xeno-MHC class II-restricted CD4(+) T-cells should have either Th1 or Th2 function.

Analysis of the T Cell Receptor Vβ Repertoire in 2,4,6-Trinitrobenzenesulfonic Acid Induced Colitis in Mice

The aim of this study was to analyze which types of T cells are at work and the specific nature of their response, using a mouse 2,4,6-trinitrobenzenesulfonic acid (TNBS) induced colitis model. The response of T cells to TNBS was analyzed by anti-TNBS mixed-lymphocyte reaction. T cell clones were established by limiting dilution. Phenotypes and T cell receptor (TCR) Vβ of T cells were analyzed by flow cytometry. Colitis was induced by administration of TNBS enemas, and lamina propria lymphocytes were isolated and analyzed. The proliferative responses to TNBS of spleen T cells were partially inhibited by the addition of antimouse CD4 or CD8 antibodies to the mixed-lymphocyte culture. Conversely, these were inhibited by the addition of both antibodies. Flow cytometric analysis showed that TCR Vβ14 T cells specifically increased in the CD8+ T cell population. We established CD8+ TCR Vβ14 T cell clones which were TNBS reactive and self-restricted. Investigation using lamina propria lymphocytes in TNBS-induced colitis revealed that the rate of CD8+ TCR Vβ14 T cells changed with histological inflammatory activity which also attained a peak on day 5 following enema administration. Both CD4+ and CD8+ T cell subsets responded to TNBS, and the rate of CD8+ TCR Vβ14 T cells changed with histological inflammatory activity in TNBS-induced colitis.