摘要:

AbstractHuman polymorphonuclear leukocytes (PMN) stimulated by lipopolysaccharide (LPS) produce interleukin‐12 (IL‐12). Both the free IL‐12 p40 chain and minute amounts of the biologically active IL‐12 p70 heterodimers are produced by PMN. Interferon‐γ (IFN‐γ) enhanced the LPS‐induced secretion of both the free IL‐12 p40 chain and the p70 heterodimer by approximately fivefold. As observed for other IL‐12‐producing cell types, the ratio of free p40 chain to p70 heterodimer secreted by LPS‐stimulated PMN was approximately 20:1. LPS induced a 100‐fold increase of IL‐12 p40 mRNA, but had minimal effect on p35 mRNA accumulation, IFN‐γ enhanced the LPS‐induced accumulation of p40 mRNA and directly induced a several‐fold increase in the accumulation of p35 mRNA. Therefore, the combined effect of LPS and IFN‐γ induced sufficient expression of both p40 and p35 to attain production of the biologically active p70 heterodimer at physiologically relevant concentrations. The ratio between p40 and p35 mRNA abundance in PMN stimulated with both LPS and IFN‐γ was approximately 200:1, explaining the secretion of the free p40 chain in much higher concentrations than the p70 heterodimer. IL‐10, an inhibitor of the production of various cytokines in PMN, also suppressed IL‐12 mRNA accumulation and secretion by PMN. Because of the important immunoregulatory function of IL‐12, in particular induction of IFN‐γ production and facilitation of T helper cell type 1 response, the ability of PMN to produce IL‐12 suggests that neutrophils may play an active role in the regulatory interact

ISSN:0014-2980    

DOI:10.1002/eji.1830250102

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractFemale NZB/W F1 mice develop an autoimmune disease similar to human systemic lupus erythematosus (SLE), and ultimately die of glomerulonephritis. Starting at the age of 16 weeks NZB/W F1 mice were treated for a period of 19 weeks with soluble interferon‐γ receptor (sIFN‐γR), anti‐IFN‐γ monoclonal antibody (mAb) or IFN‐γ. All mice treated with sIFN‐γR or anti‐IFN‐γ mAb were alive 4 weeks after the treatment was discontinued, whereas 50% of mice died in the placebo groups and 78% of the mice died in the IFN‐γ‐treated group. Histologically, there was severe membrano‐proliferative glomerulonephritis in IFN‐γ‐ and placebo‐treated mice, and minimal or no mesangioproliferative disease in mice receiving sIFN‐γR or anti‐IFN‐γ mAb. The renal mononuclear infiltrate (T lymphocytes and monocytes), expression of major histocompatibility complex class II antigen and glomerular immunoglobulin and complement deposition were reduced in those mice. These data suggest that an IFN‐γ inhibitor, such as the soluble IFN‐γR, can be used f

ISSN:0014-2980    

DOI:10.1002/eji.1830250103

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have examined the expression and responses to activation, of novel/atypical protein kinase C (PKC) isoforms ε,ζ, and δ in the T cell lymphoma cell line K‐4. The effects of 1‐h phorbol 12‐myristate 13‐acetate (PMA) and OKT3 activation of K‐4 cells on PKC isoform distribution were examined. In addition, the effects of PMA‐mediated down‐regulation on the expression of PKC ε and ζ were determined using high concentrations of PMA over 24‐ and 48‐h time periods in these cells. PKC ε expression was not altered by incubation of K‐4 cells with up to 200 ng/ml PMA over a 24‐ or 48‐h period. PKC ε was down‐regulated in a concentration‐dependent manner by PMA after both 24‐ and 48‐h of activation. Expression of PKC ε was not completely depressed, however, even at the highest concentration of the phorbol ester after 48‐h incubation with PMA. The presence of PKC ε, ζ, and δ was confirmed by immunohistochemistry with distinct patterns of expression observed. PMA‐induced PKC activation for a 1‐h period resulted in a translocation of PKC δ from resting cytoplasmic/nuclear staining to a cytoplasmic aggregate. Following 1‐h activation through the T cell receptor‐associated complex CD3, PKC δ translocated from a peri‐nuclear/cytoplasmic compartment to a putative cytoskeletal location in K‐4 cells. This translocation was time dependent and redistributed to a cytoplasmic aggregate prior to the cytoskeleton. Similarily, following 1‐h activation through the T cell receptor, PKC ζ redistributed directly to what is possibly a cytoskeletal cell compartment. The cytoplasmic distribution of PKC ζ was unaltered following activation with PMA over a 1‐h time period. There was no apparent redistribution of PKC ε cytoplasmic staining pattern following a 1‐h direct or indirect activation. These results underline the differences in individual PKC isoform distribution, and responses to different stimuli, thereby providing additional evidence for the use of discrete PKC isoform signaling pathways in T cells. Furthermore, this data underlines the differences in PMA

ISSN:0014-2980    

DOI:10.1002/eji.1830250104

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have identified two epitopes for Epstein‐Barr virus specific cytotoxic T lymphocytes (CTL) restricted by the common allele HLA‐B7. They are EBNA 3C 881–9 (QPRAPIRPI) and EBNA 3A 379–387 (RPPIFIRRL). The epitopes conform well to the recently described motif for HLA‐B7‐binding peptides (Huckzo et al.,J. Immunol.1993.151:2572). Titration of the peptides in CTL assays and detergent lysate binding assays revealed that extending the peptides at either the N or C terminus did not reduce their affinity for HLA‐B7. This behavior contrasted with HLA‐B51, which binds peptides with a similar motif to B7, and has identical amino acid residues at sites expected to form the “F” pocket of the peptide‐binding groove. HLA‐B51 also bound the peptide EBNA 3C 881–9, but was unable to bind peptides e

ISSN:0014-2980    

DOI:10.1002/eji.1830250105

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractA monoclonal antibody (mAb) raised against human acetylcholinesterase (AChE) was found to have catalytic activity. A similar phenomenon was observed in a polyclonal antibody raised against the same antigen. The antibodies were demonstrated to be pure, and no contamination with either AChE or butyryl‐cholinesterase was found. Both antibodies hydrolyzed acetylthiocholine, an AChE substrate, and the mAb followed Michaelis‐Menten kinetics. Six other mAb and one other polyclonal antibody showed no evidence of catalytic activity. This development of cholinesterase‐like behavior by certain anti‐AChE antibodies may have arisen by stable complexation of the enzyme with a substrate or inhibitor during antigen presentation. This phenomenon may have implications for the diagnostic measurement of AChE activity as well as in assessing the immunological reasons for the markedly raised AChE level in developmental conditions such as Hirschsprung's

ISSN:0014-2980    

DOI:10.1002/eji.1830250106

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have developed anin vitroassay for tetanus toxin (tt) C fragment (C‐fr) degradation. Purified endosomes (abbreviated endosomes 1101 or 1104) and lysosomes (abbreviated lysosomes 1101 or 1104) from the DRB1*1101 (Gly 86) and DRB1*1104 (Val 86) B cell lines were used to degrade125I‐labeled C‐frin vitro. Using three distinct methods of analysis, we show that the capacity of endosomes and lysosomes to degrade the tt C‐fr or tt synthetic Y‐P30 peptide differed. Using sodium dodecylsulfate‐polyacrylamide gel electrophoresis,125I‐labeled C‐fr degradation patterns observed either with endosomes 1101/1104 or lysosomes 1101/1104 are distinct both in terms of the number of fragments and the kinetics of generation of the fragments. These results were confirmed by high‐performance liquid chromatography analysis, where we observed that the elution profiles of the125I‐labeled Y‐P30 peptide digested by endosomes 1101/1104 were different compared to those obtained with lysosomes 1101/1104. Furthermore, the kinetics of degradation of125I‐labeled Y‐P30 were faster with lysosomes 1104 than with lysosomes 1101. This difference in activity of the 1101 and 1104 organelles was also found in a functional assay where we showed that the activation capacity of the P30 peptide was diminished when digested by lysosome 1104, regardless of the antigen‐presenting cell (APC) used, whereas endosomes 1101 or lysosomes 1101 modified P30 peptide in a form that discriminated between presentation by 1101 or 1104 APC. Taken together, these results suggest that the differential processing and presentation displayed by the DRB1*1101 and DRB1*1104 APC is due partly to a different enzymatic content and partly to the d

ISSN:0014-2980    

DOI:10.1002/eji.1830250107

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThelprgene has recently been shown to encode a functional mutation in the Fas receptor, a molecule involved in transducing apoptotic signals. Mice homozygous for thelprgene develop an autoimmune syndrome accompanied by massive accumulation of double‐negative (DN) CD4−8−B220+T cell receptor‐α/β+cells. In order to investigate the origin of these DN T cells, we derivedlpr/lprmice lacking major histocompatibility complex (MHC) class I molecules by intercrossing them with β2‐microglobulin (β2m)‐deficient mice. Interestingly, theselprβ2m–/– mice develop 13‐fold fewer DN T cells in lymph nodes as compared tolpr/lprwild‐type (lprWT) mice. Analysis of anti‐DNA antibodies and rheumatoid factor in serum demonstrates thatlprβ2m–/– mice produce comparable levels of autoantibodies tolprWT mice. Collectively our data indicate that MHC class I molecules control the development of DN T cells but not autoantibody production inIpr/lprmice and support the hypothesis that the majority of DN T cells may be derive

ISSN:0014-2980    

DOI:10.1002/eji.1830250108

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe aim of this present study was to investigate the role of protein kinase C (PKC), downstream of p21ras, in activating interleukin‐2 (IL‐2) gene expression. It has been reported that PKC is an effector of p21rasin T cells. Data is presented, using the potent and selective PKC inhibitor Ro 31‐8425 and transient expression of a constitutively active ras mutant, which clearly shows that PKC is not downstream of p21rasin the induction of NF‐AT and AP‐1 transcriptional activity and in the expression of IL‐2 in human Jurkat T cells. Reporter gene experiments demonstrated that NF‐χB transcriptional activity is not affected by expression of activated p21ras. The signaling pathways involving PKC activation, calcium mobilization and ras activation combine to provide the necessary components for production of IL‐2 during T

ISSN:0014-2980    

DOI:10.1002/eji.1830250109

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractIn normal antigen‐presenting cells, newly synthesized major histocompatibility complex (MHC) class II molecules associate with the invariant chain (Ii) glycoprotein in the endoplasmic reticulum (ER). They are loaded with peptides only after proteolytic removal of the Ii in post‐Golgi endocytic vesicles. Since the Ii inhibits peptide binding to MHC class II molecules, this association could protect MHC class II molecules from being loaded with endogenous peptides early after biosynthesis. If this were an important function of the Iiin vivo, MHC class II molecules synthesized in cells lacking the Ii should be loaded efficiently with short endogenous peptides in the ER; such peptides are known to be present there due to TAP‐mediated import from the cytosol. To examine this possibility, we have studied peptide loading in HeLa transfectants expressing murine H‐2AkMHC class II molecules either alone or together with an excess of Ii. Endogenous peptides could readily be extracted from conformationally intact Akαβ dimers of biosynthetically labeled Ii+cells, whereas peptide loading was greatly (>95%) diminished in the absence of Ii. Significant amounts of sodium dodecyl sulfate‐(SDS) stable 55‐kDa peptide: Akcomplexes were only found in the Ii+transfectants. In the absence of Ii, the MHC class II molecules instead formed stable complexes with long (20 and 50 kDa) polypeptides. Known Ak‐binding peptides bound stably to Akmolecules on Ii−cells, could be co‐purified with them, and were resistant to release in SDS, suggesting that poor recovery of endogenous peptides was not due to decreased stability of Ak: peptide complexes in the absence of Ii. We conclude that protection of MHC class II molecules from endogenous short peptides does not appear to be a quantitatively important function of the Ii molecule, because peptide loading is ineffic

ISSN:0014-2980    

DOI:10.1002/eji.1830250110

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe expression of recombination activating gene (RAG) products, responsible for T cell receptor (TcR) gene rearrangement, is shut off during positive selection of thymocytes. The precise stage at which this down‐regulation occurs remains somewhat controversial. We have analyzed RAG‐1 expression in thymocytes of TcR transgenic mice carried on selectingversusnon‐selecting genetic backgrounds, both byin situhybridization on thymus sections and by polymerase chain reaction amplification of RNA from sorted cells. The data from several transgenic lines indicate that RAG expression is already reduced in immature, cortical, CD4+CD8+cells in the presence of positively selecting major histocompatibility complex molecules, although complete shut‐off is not achieved until the mature, medullary, single‐positive stage. This finding has practical and theoretical significance for studies on the mechanism of positive

ISSN:0014-2980    

DOI:10.1002/eji.1830250111

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY