摘要:

AbstractCollagen arthritis is induced in inbred rats with the injection of native type II collagen. The pathogenesis of this experimental autoimmune disease is T cell dependent. This study demonstrates that collagen‐specific Tcells, derived from pathogenic and nonpathogenic rat Tcell lines, both recognize the same peptide epitope. The epitope, consisting of amino acids 58–73 of cyanogen bromide fragment 11 of type II collagen, was as effective as whole collagen in stimulating a panel of collagen‐specific rat/mouse Tcell hybridomas. This peptide may, therefore, constitute a dominant epitope for CD4+rat Tcells in their response to type II collagen. Administration of the peptide to either neonatal or adult rats prevented the subsequent induction of experimental arthritis with whole collagen, demonstrating that thein vivoresponse to this dominant epitope is, therefore, relevant in the pathogenesis of arthritis. Despite its ability to prevent collagen‐induced arthritis, administration of this peptide in incomplete Freund's adjuvant intradermally did not induce

ISSN:0014-2980    

DOI:10.1002/eji.1830230302

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractHuman immunodeficiency virus binds to CD4 T lymphocytes by interaction between its envelope glycoprotein gpl20 and the CD4 molecule. The latter is non‐covalently associated with a src‐related tyrosine kinase, p56lck. CD4 cross‐linking increases the activity of p56lck, leading to phosphorylation of several cellular substrates. We report here that gpl60/120 increases both the autophos‐phorylation of p56lckand its enzymatic activity (reflected by phosphorylation of an exogeneous substrate) in normal T cells and the HUT78 CD4+T cell line. This effect was detectable 5 min after activation and persisted for 40 min in normal T cells. It did not require gpl20 cross‐linking and was associated with phosphorylation of tyrosine residue on several proteins, as shown by phosphotyrosine Western blot analysis. The pattern of proteins phosphorylated on tyrosine residues in response to gpl20 activation was distinct from that induced by anti‐CD4 antibodies. p56lckactivation required its association with CD4, since p56lckactivity was not modified in HUT78 T cell lines expressing a truncated or mutated form of CD4 unable to associate with p56lck. Peptides mimicking residues 418 to 434 and 449 to 464 of HIV‐1 Bru gpl20, regions known to participate in gpl20 binding to CD4, also increased p56lckactivity and triggered phosphorylation of similar substrates. Taken together, these results show that gpl60/120 and derived peptides can transiently increase p56lckactivity without the need for CD4 cross‐linking. This activation led to a specific pattern of tyrosine phosphorylation on cellular proteins that may be of significance in the biological effects of the gpl20/CD4 interaction,e.g.syncytium formation and inhibition of T

ISSN:0014-2980    

DOI:10.1002/eji.1830230303

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractIn vitrohuman T lymphocyte activation requires two‐signal triggering delivered by lectins, phorbol esters or antibodies directed against surface molecules. Stimulation of adhesion molecules by CD2 and/or CD28 antibodies defines alternative activation pathways. Activation by CD2 + CD28 monoclonal antibodies induces high‐level, long‐lasting and monocyte‐independent proliferation of highly purified T cells. Limiting dilution cultures showed that CD28 in association with CD2 or CD3, without addition of exogenous cytokines, induced single‐cell proliferation. CD2 + CD28 stimulation induced long‐term interleukin (IL)‐2‐dependent autocrine proliferation of CD4+T cell clones. We tried to elucidate this long‐term proliferation by evaluating cytokine secretion and cytokine dependency. CD28 associated to CD3 or CD2 induced high levels of IL‐2, tumor necrosis factor (TNF) and IL‐4 secretion for 10 days, in contrast to CD3 alone which induced only TNF secretion. Cytokines of the monocytic lineage were also secreted, such as colony‐stimulating factor‐1, granulocyte macrophage colony‐stimulating factor or IL‐1, the latter being more specific of CD2 + CD28 activation. Blocking antibodies confirmed the crucial role of IL‐2 in CD2 + CD28 activation. Anti‐IL‐4, anti‐IL‐7 receptor or anti‐TNF antibodies had no effect on proliferation. Stimulation with CD2 + CD28 induced long‐term autocrine (at least for IL‐2) proliferation for CD4+T cells, with no evidence for the implication of another cytokine among those tested other than IL‐2. This represents a model for lo

ISSN:0014-2980    

DOI:10.1002/eji.1830230304

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractPurified HLA‐A2.1 molecules obtained by affinity chromatography of 6 × 1010Epstein Barr virus (EBV)‐transformed B lymphocytes were used in an attempt to isolate the human HLA‐A2.1‐restricted minor histocompatibility (H) peptides H‐Y and HA‐2. Fraction 18 of the high‐performance liquid chromatography (HPLC)‐separated HLA‐A2.1 peptide pool was found to contain the natural HA‐2 peptide. An HA‐2‐specific, HLA‐A2.1‐restricted cytotoxic T lymphocyte clone lysed HLA‐A2.1+HA‐2−EBV‐transformed B lymphocyte cell lines reproducibly and in a concentration‐dependent fashion in the presence of fraction 18, but not in the presence of other HPLC fractions. By contrast, H‐Y sensitizing activity was not found in any fraction. Amino acid sequencing of peptide fraction 18 revealed a mixture of peptides with maximal length of nine amino acids, in which the presence of Leu at positions 2 and 9 was dominant. Surprisingly, the HA‐2 peptide could not be mimicked by any of the peptide mixtures synthesized according to the amino acid sequences found in fraction 18. Our failure to obtain the actual amino acid sequence of the human minor H peptide HA‐2 from a peptide pool with the established pattern for binding to HLA‐A2.1 may indicate that this CTL defined minor H peptide does not

ISSN:0014-2980    

DOI:10.1002/eji.1830230305

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractX‐linked agammaglobulinemia (XLA) is a humoral immunodeficiency disease in man, characterized by an arrest in B lymphocyte differentiation at the precursor B cell stage. The structure of expressed immunoglobulin (Ig) χ light (L) chain rearrangements of nine B lymphoblastoid cell lines from one XLA patient was investigated by amplification of cDNA by the polymerase chain reaction using 5′ Vχ family‐specific primers and a 3′ χ constant region primer. Members of all four Vχ gene families were found to be utilized in Ig χ L chain rearrangements at frequencies that were consistent with random Vχ family usage. There was no preference for usage of any particular χ joining segment. Additional diversity was generated by deletions and random nucleotide insertions at the site of juxtaposition. Particular Vχ members seemed to be overrepresented in the sample. The observed homology of the VχI, VχII and VχIII region sequences, both to each other and to known germ‐line Vχ sequence indicated the absence of somatic mutations in the majority of these expressed Ig genes. In contrast of the single‐member VχIV family four different sequences were found to be expressed. That these sequences were mutated derivatives of a germ‐line VχIV element was substantiated both by sequence analysis and oligonucleotide hybridization. This finding shows that the mutation process can occur in early stages of B cell developmenti.e.before H chain class switch has occurred. The presence of these mutations is probably independent of clonal expansion since XLA patients are unable to respond to antigen. We conclude that the differentiation arrest in XLA does not preclude early onset of somatic mutation

ISSN:0014-2980    

DOI:10.1002/eji.1830230306

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractThe human granzyme B gene encodes a serine protease expressed specifically in cytoplasmic granules of cytotoxic T lymphocytes, released upon effector‐target cell interaction. Previous studies have shown that granzyme B mRNA was induced in T lymphocytes after antigenic or mitogenic stimulation. To study the regulation of human granzyme B gene expression during lymphocyte activation we analyzed its 5′ flanking region using chloramphenicol acetyl transferase (CAT) reporter gene constructs. We show that a 208‐bp fragment (‐148 to +60) containing an NF‐AT (nuclear factor of activated T cells)‐binding site promotes CAT expression in phytohemagglutinin‐activated T lymphocytes, in immobilized monoclonal anti‐CD3 antibody‐activated Jurkat T cell line while it is inactive in unstimulated PEER and Jurkat T cells lines or B Epstein‐Barr virus‐t

ISSN:0014-2980    

DOI:10.1002/eji.1830230307

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractIn order to raise antibodies synthetic peptides are often coupled to a carrier protein to provide the necessary T cell determinants. Alternatively, a short synthetic determinant with a distinct sequence motif which can be presented by major histocompatibility complex (MHC) class II toT cells, can be linked directly to a B cell epitope. Recently, it has been suggested that covalent linkage between a class II‐presentable T helper peptide and a B cell epitope is not required to induce antibodies against a B cell determinant (Sarobe et al.,Eur. J. Immunol. 1991.21: 1555). Therefore, we investigated the ability of an H‐2d‐restricted T cell determinant (AA 111–120 FERFEIFPKEK) from the influenza virus hemagglutinin, to support B cell responses to different proven B cell determinant peptides, derived from human α1‐antitrypsin. Antibodies against B cell epitopes crossreactive with native α1‐antitrypsin could be raised only when these B epitope peptides were covalently coupled to the T cell determinant through a peptide bond. No antibodies were raised against the B cell epitope when the free peptides (Tand B cell epitopes) were just mixed or when the T cell epitope was conjugated via m‐maleimidobenzoyl succinimide ester or bis‐maleimidohexane to the B cell determinant. Antibodies against the T cell determinant were raised in all cases, regardless of the mode of presentation: just mixed with or covalently coupled to the B cell determinant. The results indicate that a covalent bond between T cell and B cell determinants in general is needed to induce anti B cell determinant antibodies cross‐reactive with

ISSN:0014-2980    

DOI:10.1002/eji.1830230308

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of influenza (FLU) infection on heterotypic conjugate formation between antigen‐presenting cells and T lymphocytes has been studied with FLU‐specific T cell clones and FLU‐infected B‐lymphoblastoid cells (B‐LCL). Conjugate formation between FLU‐infected B‐LCL (FLU+B‐LCL) and T cells was found to be consistently enhanced in comparison with peptide‐sensitized or uninfected B‐LCL. Treatment of B‐LCL with exogenous neuraminidase (NA‐NAse) similarly enhanced conjugate formation indicating that increased conjugate formation may be mediated by the viral neuraminidase. Monoclonal antibody blocking experiments revealed that the contribution by CD2/LFA‐3 is increased relative to that of LFA‐l/ICAM‐1 in conjugates between FLU+B‐LCL or NANAse‐treated B‐LCL and T cell clones. In contrast, both pathways of adhesion contributed equally to conjugate formation between peptide‐sensitized B‐LCL or control B‐LCL and T cell clones. Thus, FLU infection causes increased conjugate formation between antigen‐presenting cells and T cells and skews towards CD2/LFA‐3‐dependent adhe

ISSN:0014-2980    

DOI:10.1002/eji.1830230309

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractFcγRII and FcϵRI are functionally distinct cell surface receptors for immunoglobulin (Ig); FcγRII binds IgG with low affinity, whereas FcϵRI binds IgE with high affinity, yet they are homologous in structure and sequence having extracellular regions containing two Ig‐like domains with 38% amino acid identity. Chimeric receptors derived from human FcγRII and FcγRI were produced by exchanging homologous regions of the two receptors to define binding region(s) for IgG in FcγRII and IgE in FcϵRI. Firstly, a chimeric form of the FcϵRI α chain was produced by replacing the transmembrane region and cytoplasmic tail with that of FcγRII. This mutant α chain could be expressed on the cell surface independently of associated β and γ subunits, and retained high‐affinity IgE binding, indicating that the extracellular region of the FcγRI α chain is sufficient for high‐affinity IgE binding. Secondly, to identify the role of the individual domains in Fc binding of both FcγRII and FcγRI, chimeric receptors were generated by exchanging the first extracellular domains between FcγRII and the α chain mutant and used to demonstrate that the second extracellular domain of both receptors contains region(s) directly involved in Ig binding. Additional chimeric receptors were constructed to localize the Ig interactive regions in domain two of FcγRII and FcγRI; these identified a single region of IgG binding in FcγRII located between residues Ser136to Val169, and at least three independent IgE binding regions in the FcγRI α chain, between residues Trp87to Lys128, Tyr129

ISSN:0014-2980    

DOI:10.1002/eji.1830230310

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractBiological activities have been determined for a series of 18 peptides based on the C‐terminal sequence of human or rat C5a. Lysosomal enzyme release was tested in two cell types, the promyelotic leukemia cell line U937 and polymorphonuclear leukocytes. In addition, an ATP‐release assay with guinea pig platelets was performed. It was demonstrated that the C‐terminal octapeptide 67‐74 of human C5a represents the minimal sequence required to induce a measurable biological signal in all assays. Extending this peptide to a length of 21 amino acids produced at best only a slight enhancement of potency. Amino acid replacements with either tryptophanyl or phenylalanyl residues in positions between 65–69 either increased potency (at position 67), or abrogated potency (at position 66) in the two lysosomal enzyme assays. N‐terminal acylation with the fluorenylmethoxy‐carbonyl‐aminohexanoyl group slightly enhanced C5a potency. In desensitization experiments with guinea pig platelets all peptides with a C5a activity were able to desensitize not only the C5a but also th

ISSN:0014-2980    

DOI:10.1002/eji.1830230311

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY