摘要:

AbstractThe peptide‐binding properties of the nonclassical major histocompatibility complex (MHC) class 1b molecule Qa‐1 were investigated using a transfected hybrid molecule composed of the α1 and α2 domains of Qa‐1band the α3 domain of H‐2Db. This allowed the use of a monoclonal antibody directed against H‐2Dbwhilst retaining the peptide‐binding groove of Qa‐1b. By comparison with classical MHC class I molecules, intracellular maturation of the chimeric molecule was inefficient with weak intracellular association with β2‐microglobulin. However, at the cell surface the hybrid molecules were stably associated with β2‐microglobulin and were recognized by cytotoxic T lymphocyte (CTL) clones specific for the Qa‐1b‐presented peptide Qdm (AMAPRTLLL). A whole‐cell binding assay was used to determine which residues of Qdm were important for binding to Qa‐1band CTL clones served to identify residues important for T cell recognition. Substitutions at position 1 and 5 did not reduce the efficiency of binding and had little effect on CTL recognition. In contrast, substitutions at position 9 resulted in loss of MHC class I binding. Mass spectrometric analysis of peptides eluted from immunopurified Qa‐1b/Dbmolecules indicated that Qdm was the dominant peptide. The closely related peptide, AMVPRTLLL, which is derived from the signal sequence of H‐2Dk, was also present, although it was considerably less abundant. The mass profile suggested the presence of additional peptides the majority of which consisted of eight to ten amino acid residues. Finally, the finding that a peptide derived fromKlebsiella pneumoniaecan bind raises the possibility that this non‐classical MHC class I molecule may play a role in the presen

ISSN:0014-2980    

DOI:10.1002/eji.1830270902

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractBoth interleukin‐7 (IL‐7) and IL‐7 receptor (R) gene knockout (IL‐7−/−and IL‐7R−/−) mice were employed in order to directly investigate the importance of the IL‐7 and IL‐7R signaling pathway for the development of intestinal intraepithelial lymphocytes (IEL). Loss of the IL‐7R‐specific gene resulted in complete deficiency of the γδ T cell lineage with lack of Vγ4‐ and Vγ7‐specific messages in the epithelium of the gastrointestinal (GI) tract in comparison to control mice of the same genetic background (∼ 40%). Disruption of the IL‐7‐specific gene resulted in marked, but not complete depletion of γδ T cells (2–3%) in IEL. Furthermore, mRNA for both Vγ4 and Vγ7 genes were detected in the γδ IEL subset of IL‐7−/−mice. The subtle differences between IL‐7−/−and IL‐7R−/−mice suggest that although IL‐7 controls most of the expansion and/or development of γδ IEL, another ligand binding to the IL‐7R also plays a discernable role. Furthermore, αβ IEL developed more slowly in IL‐7R−/−mice when compared with ligand knockouts; however, the frequency of IEL T cells subsequently increased with age and normal levels of CD3+T cells expressing the αβ TCR were detected by 2 and 3 months of age in IL‐7−/−and IL‐7R−/−mice, respectively. The direct comparison of IL‐7 and IL‐7R−/−mice clearly supports the hypothesis that both IL‐7 and

ISSN:0014-2980    

DOI:10.1002/eji.1830270903

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractPositive selection is an obligatory step during intrathymic T cell differentiation. It is associated with rescue of short‐lived, self major histocompatibility complex (MHC)‐restricted thymocytes from programmed cell death, CD4/CD8 T cell lineage commitment, and induction of lineage‐specific differentiation programs. T cell receptor (TCR) signaling during positive selection can be closely mimicked by targeting TCR on immature thymocytes to cortical epithelial cellsin situvia hybrid antibodies. We show that selection of CD4 T cell lineage cells in mice deficient for MHC class I and MHC class II expression can be reconstitutedin vivoby two separable T cell receptor signaling steps, whereas a single TCR signal leads only to induction of short‐lived CD4+CD8laintermediates. These intermediates remain susceptible to a second TCR signal for 12‐48 h providing an estimate for the duration of positive selectionin situ.While both TCR signals induce differentiation steps, only the second one confers long‐term survival on immature thymocytes. In further support of the two‐step model of positive selection we provide evidence that CD4 T cell lineage cells rescued by a single hybrid antibody pulse in MHC class II‐deficient mice are pre‐select

ISSN:0014-2980    

DOI:10.1002/eji.1830270904

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractMouse mammary tumor virus (MMTV) (SW) caused a high incidence (65%) of pregnancy‐dependent adenocarcinomas in BALB/c(SW) mice infected as new‐borns by suckling their mothers' milk. These tumors were type B adenocarcinomas which developed early, at about 1 year of age. Uninfected breeding females and those infected at an age of 8 weeks by injection of virus had the same low incidence of malignant tumors (13%), and the tumors developed later (at approx. 23–24 months). The low incidence of tumors in adult‐infected mice was correlated with partial infection of the mammary glands, and delayed transmission of MMTV(SW) to the offspring. Although the virus was rapidly disseminated in both types of infection, the responses of neonatally infected and adult‐infected mice to MMTV(SW) infection and viral superantigen (vSAG) presentation were different. Activation by and presentation of the vSAG was impaired in mice infected neonatally, and tolerance induction by clonal deletion was delayed. Local activation was dramatic in mice infected as adults and clonal deletion followed rapidly. Although interaction between B and T cells is needed for completion of the virus life cycle and viral amplification, the strong local immune response to MMTV(SW) in adult‐infected mice limits mammary gland infection, and protects them against mammary tumor

ISSN:0014-2980    

DOI:10.1002/eji.1830270905

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractCD43 (leukosialin), a sialylated glycoprotein expressed on the surface of most hematopoietic cells, has been implicated in cell adhesion and signaling. However, its precise physiological function remains unclear. We used mouse CD43 (mCD43)‐immunoglobulin enhancer‐transgenic (TG) mice to study the role of mCD43in vivo.Previous work revealed that mCD43 expression on mature B cells in these mice resulted in immunodeficiency to T‐dependent (TD) antigens (Ag), possibly by impairing B‐T cell interactions. In the present study we have immunized the TG mice with the T‐independent (TI) Ag fluorescein‐(Fl) lipopolysaccharide (LPS) (TI type 1 Ag) and Fl‐Ficoll (TI type 2 Ag). Surprisingly, the mCD43‐Ig enhancer expressing mice were impaired in their ability to mount humoral responses to both Fl‐LPS and Fl‐Ficoll, and had decreased numbers of cells responding to Agin vivo.Flow cytometric analysis was performed on peritoneal B‐1 cells, a population which often plays a major role in humoral responses to TI Ag such as bacterial Ag. This analysis revealed similar B220, IgM and CD5 expression patterns for the TG and nontransgenic (NTG) B‐1 cells. In addition, purified peritoneal B‐1 cells from TG and NTG mice were able to respond to LPS. Stimulation of splenic B cellsin vitrowith Fl‐LPS and Fl‐Ficoll revealed that, in contrast to NTG B cell responses, TG B cell responses could not be enhanced by co‐culture with T cells. However, soluble T cell factor enhancement of the TG B cell responses was normal. These data suggest that the mCD43 expression on B cells may inhibit cell interactions that are important for enhanced TI Ag responses. The anti‐adhesive forces of mucins in general may thus be critical in regulating

ISSN:0014-2980    

DOI:10.1002/eji.1830270906

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe interaction of B lymphocytes with phagocytes is critical for shaping the humoral immune response, as well as various aspects of normal and malignant B cell development, and has therefore been studied by immunologists in great detail. However, one potential outcome of this confrontation is often neglected, namely the mutagenicity of phagocytes to B lymphocytes. We are interested in phagocyte‐induced B cell mutagenesis and have conducted a feasibility study on the utility of a transgenic reporter assay to evaluate mutant frequencies in B cells that have encountered phagocytes. Anin vitroco‐incubation system was designed in which splenic lipopolysaccharide (LPS) blasts carrying a phage Δ‐derivedlacItransgene were exposed to pristane‐elicited peritoneal exudate cells (PEC). Mutant frequencies in LPS blasts were significantly increased (up to 6‐fold) when the cells were co‐incubated with PEC that had been stimulated by phorbol myristate acetate to undergo an oxidative burst. ThelacI‐based transgenic mutation assay proved also useful for assessing mutagenicityin vivo, as demonstrated by the detection of elevated mutant frequencies in the spleen (3‐fold) and the inflammatory granuloma (4.7‐fold) obtained from pristane‐treated mice. We propose to utilize thelacI‐based transgenic mutagenesis assay as a tool to evaluate mutational levels during normal and aberrant

ISSN:0014-2980    

DOI:10.1002/eji.1830270907

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe aims of the present work were to elucidate the biochemical properties of interleukin‐1β (IL‐1β) in psoriatic scales to get information on the processing of epidermal IL‐1β in psoriasis, and to elucidate whether the IL‐1β in psoriatic scales possesses biological activity. By means of ion exchange chromatography, IL‐1β in extracts of psoriatic scales was purified to a stage where it could be analyzed with electrophoretic methods and immunoblotting. Compared to mature recombinant human IL‐1β (Ala 117 IL‐1β), IL‐1β in psoriatic scales had a slightly higher apparent molecular mass and a more acidic isoelectric point, as revealed by two‐dimensional electrophoresis under denaturing conditions. Isoelectric focusing under non‐denaturing conditions of IL‐1β partially purified from psoriatic scales, or from non‐inflamed plantar stratum corneum (Nylander Lundqvist, E., Bäck, O. and Egelrud, T.,J. Immunol.1996.157: 1699), and of mature IL‐1β, followed by immunoblotting with IL‐1β‐specific antibodies, showed that psoriatic scales contained two components with IL‐1β‐like immuno‐reactivity which were isoelectric at pH 6.1 and 6.3, respectively. Theses components could also be detected in extracts of plantar stratum corneum, which also contained small amounts of an IL‐1β‐like component isoelectric at pH 6.9. Mature IL‐1β was isoelectric at pH 6.9. No IL‐1β‐like biological activity could be detected in crude extracts of psoriatic scales. These extracts also contained high amounts of IL‐1 receptor antagonist. Partially purified preparations of IL‐1β from psoriatic scales, in which an apparently total separation of IL‐1β and IL‐1 receptor antagonist had been achieved, could induce expression of E‐selectin in human umbilical vein endothelial cells. This activity was inhibited by antibodies specific for IL‐1β, but not by antibodies specific for IL‐1α. It is concluded that psoriatic scales contain biologically active IL‐1β, which has been processed by a mechanism which may be similar to that present in non‐

ISSN:0014-2980    

DOI:10.1002/eji.1830270908

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractRecent studies from our laboratory have indicated that protein tyrosine phosphatase (PTPase) inhibitors can down‐modulate the tumor necrosis factor (TNF)‐mediated activation of the nuclear transcription factor NF‐xB in ML‐1a, a monocytic cell line (Singh and Aggarwal,J. Biol. Chem.1995:270: 10631). Since TNF is one of the major inducers of various adhesion molecules in human endothelial cells and their expression is known to require the activation of NF‐xB, we examined the effect of PTPase inhibitors on the TNF‐mediated induction of intracellular adhesion molecule (ICAM)‐1, vascular cell adhesion molecule (VCAM)‐1 and endothelial leukocyte adhesion molecule (ELAM)‐1. Like ML‐1a, human dermal microvessel endothelial cells (MVEC) treated with TNF rapidly activated (within 30 min) NF‐xB; this effect was completely abolished by co‐treatment with phenylarsine oxide (PAO), a specific inhibitor of PTPase. The induction of ICAM‐1, VCAM‐1, and ELAM‐1 by TNF in MVEC occurred within 6 h and was also completely down‐regulated by PAO in a dose‐dependent manner. PAO was found to be effective even when added 3 h after TNF, suggesting a rapid mode of action of this inhibitor. Besides PAO, other inhibitors of PTPase, including pervanadate and diamide, also blocked TNF‐dependent NF‐xB activation and induction of all the three adhesion proteins. Consistent with these results, the attachment of monocytes to MVEC was also blocked by the PTPase inhibitors. Thus, overall, our results demonstrate that a PTPase is involved either directly or indirectly in the pathway leading to the induction of endothelial cell adhesion molecules by TNF. Because of their role in cell adhesion, PTPase may provide a novel target of drug development for treatment of inflammation

ISSN:0014-2980    

DOI:10.1002/eji.1830270909

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractMutations in the gene for Bruton's tyrosine kinase result in the B cell differentiation defects X‐linked agammaglobulinemia in man and X‐linked immunodeficiency in mice. Here we describ the generation of two yeast artificial chromosome (YAC)‐transgenic mouse strains in which high‐level expression of humanBtkis provided by endogenous regulatory cis‐acting elements that are present on a 340‐kb transgene, Yc340‐hBtk.The expression pattern of the transgenic humanBtkwas found to parallel that of the endogenous murine gene. When the Yc340‐hBtk‐transgenic mice were mated onto aBtk‐deficient background, thexidB cell defects were fully corrected: conventional and CD5+B‐1 B cells were present in normal numbers, serum IgM and IgG3 levels as well as responses to T cell‐independent type II antigens were in the normal ranges.In vivocompetition experiments inBtk+/−female mice demonstrated that in the conventional B cell population the Yc340‐hBtktransgene could fully compensate the absence of expression of endogenous murineBtk.We conclude that in the YAC‐transgenic miceBtkis appropriately expressed in the context o

ISSN:0014-2980    

DOI:10.1002/eji.1830270910

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractWe have observed that CD4 T lymphocytes from human immunodeficiency virus (HIV)‐infected patients marginally express interleukin‐2 receptor (IL‐2R)β and IL‐2Rγ chains which are essential for IL‐2 signal transduction. To analyze this observation further, we studied the influence of gp120 on the cell surface expression of IL‐2Rβ and IL‐2Rγ by purified CD4 lymphocytesin vitro.Cross‐linking of the T cell receptors of these lymphocytes initiates entry into the cell cycle as measured by CD69 and CD71 cell surface expression and [3H]thymidine incorporation. It also induces the cell surface expression of IL‐2Rβ and IL‐2Rγ. We have shown that treatment of the CD4 T lymphocytes with HIV‐1 gp120 before anti‐CD3 stimulation impedes cell cycle progression as measured by reduced CD71 expression and inhibition of [3H]thymidine incorporation. Furthermore, cell surface expression of IL‐2Rβ and IL‐2Rγ subunits, which form the functional intermediate‐affinity IL‐2R, are significantly inhibited. More importantly, addition of exogenous IL‐2 does not restore the proliferation of the CD4 T cells treated with gp120, suggesting that cells are anergic and/or that the remaining IL‐2R are not functional. This is the first study of IL‐2Rβ and IL‐2Rγ dysregulation in the context of HIV infection and sh

ISSN:0014-2980    

DOI:10.1002/eji.1830270911

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY