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Anita Mehta-Damani Sergiusz Markowicz Edgar G. Engleman 《European journal of immunology》1995,25(5):1206-1211
The conditions required for sensitizing naive T cells to nominal antigen are poorly understood. In this report we describe an in vitro system for generating antigen-specific CD4+ T cells from previously unprimed individuals. Freshly isolated CD4+ T cells were cultured with keyhole limpet hemocyanin (KLH), sperm whale myoglobin (SWM), or human immunodeficiency virus (HIV) gp 160, antigens to which most persons have not been sensitized, in the presence of either dendritic cells (DC) or macrophages (MΦ). In short-term (< 8 days) cultures, CD4+ T cells or their CD4+, CD45RA (naive) subpopulation mounted significant proliferative responses to KLH, SWM, and HIV gp160, but only if the antigens were presented by DC. In contrast, CD4+, CD45RO (memory) T cells responded poorly to these antigens, although they responded vigorously to tetanus toxoid, a recall antigen, presented by either DC or MΦ. KLH- and SWM-specific CD4+ T cell lines were established from the starting population that had been sensitized in vitro, following repeated stimulation with antigen and MΦ in medium supplemented with interleukin-2 and interleukin-4. Despite the continued presence of these cytokines during T cell expansion, the expanded lines retained their ability to respond to the priming antigen in the absence of exogenous cytokines. When the CD45RA and CD45RO subpopulations were sensitized and expanded separately, the CD45RA cells alone gave rise to antigen-specific T cell lines, while the CD45RO cells proliferated nonspecifically. These results demonstrate that human naive CD4+ T cells can be sensitized in vitro to nominal antigens presented by DC and that the sensitized cells can be expanded into long-term lines that retain their antigen specificity. 相似文献
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Role of envelope glycoprotein carbohydrate in human immunodeficiency virus (HIV) infectivity and virus-induced cell fusion 总被引:16,自引:2,他引:14 下载免费PDF全文
Human immunodeficiency virus (HIV) envelope glycoprotein interactions with cell surface CD4 are involved in both virion infectivity and virally mediated cell fusion. D-mannose-specific lectins such as Con A specifically blocked virion infectivity and cell fusion. Studies with a recombinant vaccinia virus containing the HIV envelope gene demonstrated that Con A-mediated inhibition of HIV-induced fusion involved lectin binding to the viral envelope glycoprotein. These results indicate the importance of envelope glycosylation in the pathobiology of HIV infection, and suggest potential mechanisms for interfering with HIV infectivity and cytopathology. 相似文献
5.
Berbaum KS; el-Khoury GY; Franken EA Jr; Kathol M; Montgomery WJ; Hesson W 《Radiology》1988,168(2):507-511
The effect of knowledge of localizing symptoms and signs in the detection of fractures was studied. Forty radiographs of the extremities were examined twice by seven radiologists; the sessions were separated by 4 months. In 26 cases, a subtle fracture was present; 14 cases were normal. In half of the cases at each session, the precise location of pain, tenderness, or swelling was provided. The observer was asked to determine if the case was normal or abnormal (provide the exact location of the fracture) and to indicate the degree of confidence in the diagnosis. Responses were converted to a numeric scale for analysis. Analysis of receiver operator characteristic parameters indicates that clues regarding location of trauma facilitate detection of fractures. The improvement is based largely on an increased true-positive rate without an increased false-positive rate, regardless of the decision criteria of the radiologist (overall willingness to "overread" or "underread"). This has direct clinical applicability and reinforces the plea of radiologists for precise clinical information. 相似文献
6.
S Lewis S Avera M Engleman J Beumer 《The International journal of oral & maxillofacial implants》1989,4(2):147-152
Improper implant angulation is one of the most difficult problems to overcome in the fabrication of implant-supported and implant-retained restorations. Several techniques using the "UCLA" abutment have been developed to solve these problems. The creation of large screw-access holes for moderate angulation and the fabrication of telescopic copings and overlay castings for severe angulation problems are discussed. 相似文献
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Role of B70/B7-2 in CD4+ T-cell immune responses induced by dendritic cells. 总被引:6,自引:0,他引:6 下载免费PDF全文
F F Fagnoni M Takamizawa W R Godfrey A Rivas M Azuma K Okumura E G Engleman 《Immunology》1995,85(3):467-474
Dendritic cells (DC) are potent antigen-presenting cells (APC). However, the molecular basis underlying this activity remains incompletely understood. To address this question, we generated murine monoclonal antibodies (mAb) against human peripheral blood-derived DC. One such antibody, designated IT209, stained differentiated DC and adherent monocytes, but failed to stain freshly isolated peripheral blood mononuclear cells (PBMC). The antigen recognized by IT209 was identified as B70 (B7-2; also recently identified as CD86). Using this mAb we studied the role of B70 in CD4+ T-cell activation by DC in vitro. IT209 partly inhibited the proliferative response of CD4+ T cells to allogeneic DC and to recall antigens, such as tetanus toxoid (TT) and purified protein derivative (PPD) of tuberculin, presented by autologous DC. More importantly, the mAb had a potent inhibitory effect on the primary response of CD4+ T cells to autologous DC pulsed with human immunodeficiency virus (HIV) gp160 or keyhole limpet haemocyanin (KLH). Adherent monocytes, despite their expression of B70, failed to induce T-cell responses to these antigens. IT209-mediated inhibition of CD4+ T-cell responses was equivalent to that produced by anti-CD25 mAb, whereas an anti-CD80 mAb was only marginally inhibitory and did not augment the effect of IT209. These findings indicate that the B70 antigen plays an important role in DC-dependent CD4+ T-cell activation, particularly in the induction of primary CD4+ T-cell responses to soluble antigens. However, since activated monocytes, despite their expression of B70, failed to prime naive T cells to these antigens, our results suggest that additional molecules contribute to the functions of DC in CD4+ T-cell activation. 相似文献
9.
J-L Stievenart EA Cabanis P Menard J Knoplioch A Lopez J Tamraz M-T Iba-Zizen B Philippe G Prevost J-C Bertrand 《Surgical and radiologic anatomy : SRA》1993,15(1):47-54
Summary In view of the variety of 3D representation techniques, a clinical study was carried out in order to evaluate their respective usefulness. It appears that a single technique cannot be claimed to be valid for all clinical situations and that a combination of representations brings more relevant information. Among the different techniques a clear delineation must be established between those which allow the accurate definition of landmarks (multiplanar reformation, surface representation), and those which do not (integral shading, reconstructed radiology). The main point is the possibility to recognize anatomical landmarks on these latter modes and to choose oblique cut planes in relation to them. Visualization quality is strongly dependent upon the acquisition protocol which must provide a spatial resolution as isotropic as possible.
Une revue de différents modes de visualisation en haute résolution d'un objet volumique avec des applications
Résumé Face à la variété des techniques de représentation 3D une étude clinique a été conduite pour évaluer leurs utilités respectives. Il apparait qu'une technique unique ne peut pas convenir à toutes les situations cliniques et qu'une combinaison de différents modes de présentation apporte une information plus pertinente. Parmi les différentes techniques une distinction claire doit être établie entre celles qui autorisent la prise de repères précis (reformatage multiplanaire, représentation de surface), et celles qui ne le permettent pas (ombrage intégral, radiologie reconstruite). Le point principal est la possibilité de reconnaître des repères anatomiques sur ces derniers modes et de choisir des plans de coupe en relation avec eux. La qualité de la visualisation dépend étroitement du protocole d'acquisition qui doit fournir une résolution aussi isotrope que possible.相似文献
10.
Igarashi S; Takiyama Y; Cancel G; Rogaeva EA; Sasaki H; Wakisaka A; Zhou YX; Takano H; Endo K; Sanpei K; Oyake M; Tanaka H; Stevanin G; Abbas N; Durr A; Rogaev EI; Sherrington R; Tsuda T; Ikeda M; Cassa E; Nishizawa M; Benomar A; Julien J; Weissenbach J; Tsuji S 《Human molecular genetics》1996,5(7):923-932
Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative
disorder caused by unstable expansion of a CAG repeat in the MJD1 gene at
14q32.1. To identify elements affecting the intergenerational instability
of the CAG repeat, we investigated whether the CGG/GGG polymorphism at the
3' end of the CAG repeat affects intergenerational instability of the CAG
repeat. The [expanded (CAG)n-CGG]/[normal (CAG)n- GGG] haplotypes were
found to result in significantly greater instability of the CAG repeat
compared to the [expanded (CAG)n- CGG]/[normal (CAG)n-CGG] or [expanded
(CAG)nGGG]/[normal (CAG)n-GGG] haplotypes. Multiple stepwise logistic
regression analysis revealed that the relative risk for a large
intergenerational change in the number of CAG repeat units (< -2 or >
2) is 7.7-fold (95% CI: 2.5-23.9) higher in the case of paternal
transmission than in that of maternal transmission and 7.4-fold (95% CI:
2.4-23.3) higher in the case of transmission from a parent with the
[expanded (CAG)n-CGG]/[normal (CAG)n-GGG] haplotypes than in that of
transmission from a parent with the [expanded (CAG)n-CGG]/[normal
(CAG)n-CGG] or [expanded (CAG)n- GGG]/[normal (CAG)n-GGG] haplotypes. The
combination of paternal transmission and the [expanded (CAG)n-CGG]/[normal
(CAG)n-GGG] haplotypes resulted in a 75.2-fold (95% CI: 9.0-625.0) increase
in the relative risk compared with that of maternal transmission and the
[expanded (CAG)n-CGG]/[normal (CAG)n-CGG] or [expanded (CAG)n- GGG]/[normal
(CAG)n-GGG] haplotypes. The results suggest that an inter- allelic
interaction is involved in the intergenerational instability of the
expanded CAG repeat.
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