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D J Moss

Publications and source records attributed to D J Moss.

At least 73 records · Page 4Linked to original sources
PubMed1995

T cell receptor repertoire for a viral epitope in humans is diversified by tolerance to a background major histocompatibility complex antigen.

Two unusual characteristics of the memory response to the immunodominant Epstein-Barr virus (EBV) epitope FLRGRAYGL, which associates with HLA B8, have provided an unique opportunity to investigate self tolerance and T cell receptor (TCR) plasticity in humans. First, the response is exceptionally restricted, dominated by cytotoxic T lymphocytes (CTL) with identical TCR protein sequences (Argaet, V. P., C. W. Schmidt, S. R. Burrows, S. L. Silins, M. G. Kurilla, D. L. Doolan, A. Suhrbier, D. J. Moss, E. Kieff, T. B. Sculley, and I. S. Misko. 1994. J. Exp. Med. 180:2335-2340). Second, CTL expressing this receptor are cross-reactive with the alloantigen HLA B* 4402 on uninfected cells (Burrows, S. R., R. Khanna, J. M. Burrows, and D. J. Moss. 1994. J. Exp. Med. 179:1155-1161). No CTL using this conserved public TCR could be reactivated from the peripheral blood of EBV exposed individuals expressing both HLA B8 and B*4402, demonstrating the clonal inactivation of potentially self-reactive T cells in humans. A significant FLRGRAYGL-specific response was still apparent, however, and TCR sequence analysis of multiple CTL clones revealed an oligoclonal TCR repertoire for this determinant within these individuals, using diverse V and J gene segments and CDR3 regions. In addition, a significant public TCR component was identified in which several distinct alpha/beta rearrangements are shared by CTL clones from a number of unrelated HLA B8+, B*4402+ donors. The striking dominance of public TCR in the response to this EBV epitope suggests a strong genetic bias in TCR gene recombination. Fine specificity analysis using peptide analogues showed that, of six different antigen receptors for FLRGRAYGL/HLA B8, none associate closely with the peptide's full array of potential TCR contact residues. Whereas the HLA B*4402-cross-reactive receptor binds amino acids toward the COOH terminus of the peptide, others preferentially favor an NH2-terminal determinant, presumably evading an area that mimics a structure presented on HLA B*4402. Thus, tolerance to a background major histocompatibility antigen can effectively diversify the TCR repertoire for a foreign epitope by deflecting the response away from an immunodominant combination of TCR-binding residues.

Amino Acid Sequence↗
PubMed1995

Minimal epitopes expressed in a recombinant polyepitope protein are processed and presented to CD8+ cytotoxic T cells: implications for vaccine design.

The epitopes recognized by CD8+ cytotoxic T lymphocytes (CTL) are generated from cytosolic proteins by proteolytic processing. The nature of the influences exerted by the sequences flanking CTL epitopes on these processing events remains controversial. Here we show that each epitope within an artificial polyepitope protein containing nine minimal CD8+ CTL epitopes in sequence was processed and presented to appropriate CTL clones. Natural flanking sequences were thus not required to direct class I proteolytic processing. In addition, unnatural flanking sequences containing other CTL epitopes did not interfere with processing. The ability of every CTL epitope to be effectively processed from a protein containing only CTL epitopes is likely to find application in the construction of recombinant polyepitope CTL vaccines.

Amino Acid Sequence↗
PubMed1995

Induction of protective cytotoxic T cells to murine cytomegalovirus by using a nonapeptide and a human-compatible adjuvant (Montanide ISA 720).

The use of synthetic peptides representing cytotoxic T-cell (CTL) epitopes for human vaccination requires the identification of a suitable adjuvant formulation. A single immunization with Montanide ISA720/tetanus toxoid/YPHFMPTNL protected mice against murine cytomegalovirus and induced epitope-specific CTL. Such formulations will find application in peptide-based CTL anti-viral vaccines.

Adjuvants, Immunologic↗
PubMed1995

Immune regulation in Epstein-Barr virus-associated diseases.

Epstein-Barr virus (EBV) is a member of the human herpesvirus family and, like many other herpesviruses, maintains a lifelong latent association with B lymphocytes and a permissive association with stratified epithelium in the oropharynx. Clinical manifestations of primary EBV infection range from acute infectious mononucleosis to an asymptomatic persistent infection. EBV is also associated with a number of malignancies in humans. This review discusses features of the biology of the virus, both in cell culture systems and in the natural host, before turning to the role of the immune system in controlling EBV infection in healthy individuals and in individuals with EBV-associated diseases. Cytotoxic T cells that recognize virally determined epitopes on infected cells make up the major effector arm and control the persistent infection. In contrast, the options for immune control of EBV-associated malignancies are more restricted. Not only is antigen expression restricted to a single nuclear antigen, EBNA1, but also these tumor cells are unable to process EBV latent antigens, presumably because of a transcriptional defect in antigen-processing genes (such as TAP1 and TAP2). The likelihood of producing a vaccine capable of controlling the acute viral infection and EBV-associated malignancies is also discussed.

Antibody Formation↗
PubMed1994

Dominant selection of an invariant T cell antigen receptor in response to persistent infection by Epstein-Barr virus.

To examine T cell receptor (TCR) diversity involved in the memory response to a persistent human pathogen, we determined nucleotide sequences encoding TCR-alpha and -beta chains from HLA-B8-restricted, CD8+ cytotoxic T cell clones specific for an immunodominant epitope (FLRGRAYGL) in Epstein-Barr virus (EBV) nuclear antigen 3. Herein, we show that identical TCR protein sequences are used by clones from each of four healthy unrelated virus carriers; a clone from a fifth varied conservatively at only two residues. This dominant selection of alpha and beta chain rearrangements suggest that a persistent viral infection can select for a highly focused memory response and indicates a strong bias in gene segment usage and recombination. A novel double-step semiquantitative polymerase chain reaction (PCR) procedure and direct sequencing of amplified TCR cDNA from fresh lymphocytes derived from three HLA-B8 individuals detected transcripts specific for the conserved beta chain in an EBV-seropositive donor but not in two seronegative donors. This report describes an unprecedented degree of conservation in TCR selected in response to a natural persistent infection.

Amino Acid Sequence↗
PubMed1994

An alloresponse in humans is dominated by cytotoxic T lymphocytes (CTL) cross-reactive with a single Epstein-Barr virus CTL epitope: implications for graft-versus-host disease.

The phenomenon of T cell allorecognition is difficult to accommodate within the framework of a T cell repertoire positively selected in the thymus, unless allorecognition results from the cross-reactions of self-major histocompatibility complex restricted T cells. Herein, we demonstrate the dual specificity of cytotoxic T lymphocyte (CTL) clones for the immunodominant Epstein-Barr virus (EBV) epitope FLRGRAYGL, presented on HLA-B8, and the alloantigen HLA-B*4402. CTL which recognized peptide FLRGRAYGL in association with HLA-B8 could be reactivated in vitro from healthy individuals who had been exposed previously to EBV, using stimulator cells expressing the cross-reacting alloantigen HLA-B*4402. Limiting dilution analysis of the alloresponse to HLA-B*4402 in eight healthy individuals revealed that HLA-B8+, EBV-sero+ donors had higher CTL precursor frequencies for alloantigen HLA-B*4402 than EBV-sero- control donors. It is surprising that the majority (65-100%) of anti-HLA-B*4402 CTL, generated in limiting dilution mixed lymphocyte reactions between responder cells from HLA-B8+, EBV-sero+ individuals and HLA-B*4402+ stimulators, also recognized the EBV CTL epitope FLRGRAYGL/HLA-B8. In contrast to previous studies showing extensive diversity in the T cell repertoire against individual alloantigens, these data demonstrate that the response to an alloantigen can be dominated by CTL cross-reactive with a single viral epitope, thus illustrating a possible mechanism for the frequent clinical association between herpesvirus exposure and graft-versus-host disease after bone marrow transplants.

Amino Acid Sequence↗
PubMed1994

Potential antigenic targets on Epstein-Barr virus-associated tumours and the host response.

There is considerable variation in the degree of expression of viral genes among different tumours associated with Epstein-Barr virus (EBV). Immune control of tumours in immunosuppressed patients (immunoblastic lymphomas) can be exercised through a range of epitopes from cytotoxic T lymphocytes (CTL) covering the full spectrum of latent EBV gene products. A subunit vaccine based on an EBV CTL epitope from one of the latent genes is about to undergo human trial. The options for immune control of Burkitt's lymphoma are more restricted. Antigen expression is limited to a single nuclear antigen, EBNA1, and Burkitt's lymphoma cells are unable to process EBV latent antigens, presumably because of a transcriptional defect in TAP1 and TAP2 genes. In contrast with earlier suggestions that EBNA1 is not a target for CTL, there is a class II-restricted epitope within EBNA1. EBV-infected B cells are unable to process this epitope endogenously. The most promising strategy for developing a vaccine against these tumours is to use a single subunit vaccine that incorporates multiple CTL epitopes from several human pathogens.

Amino Acid Sequence↗
PubMed1994

Endoplasmic reticulum signal sequence facilitated transport of peptide epitopes restores immunogenicity of an antigen processing defective tumour cell line.

The identification of MHC-restricted and tumour-specific cytotoxic T lymphocytes (CTLs) provides strong evidence in support of T cell-mediated immune surveillance against human tumour cells. These CTLs recognize short peptides derived from tumour-associated antigens in conjunction with class I molecules expressed on tumour cells. In contrast to these observations there are now numerous examples to suggest that a number of tumours escape this CTL-mediated control either by down-regulating accessory molecules or by blocking the intracellular processing of tumour-specific antigens. Recently a number of tumour cell lines have been identified which display a transcriptional deficiency of transporters associated with antigen processing (also referred to as TAP). The Epstein-Barr virus (EBV)-associated tumour, Burkitt's lymphoma (BL), is a classic example in this category. In the present study we have restored class I-restricted antigen processing in a BL cell line by transfecting a minigene expression vector encoding a CTL epitope derived from EBV linked to an endoplasmic reticulum translocation signal sequence. These minigene transfected BL cells were not only susceptible to lysis by virus-specific CTL but were also capable of efficiently activating an antigen-specific CTL response. Interestingly, the immunogenicity of these BL cells was not affected by the significantly down-regulated expression of adhesion molecules such as LFA1 alpha, LFA1 beta and LFA3. These findings suggest that resistance of tumour cells to CTL-mediated immune control can be reversed if the relevant peptide epitopes are appropriately presented on the cell surface.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Heterogeneity within the Epstein-Barr virus nuclear antigen 2 gene in different strains of Epstein-Barr virus.

DNA isolated from biopsies of endemic Burkitt's lymphoma (BL) from New Guinea was analysed for the presence of Epstein-Barr virus (EBV) sequences using the polymerase chain reaction. Primers were designed to amplify sequences within the Epstein-Barr virus nuclear antigen (EBNA) 1 and 2 genes. These analyses detected the EBNA1 sequence in all the biopsies studied. Additional sets of primers directed against the EBNA2 gene were used in order to categorize the EBV strains as A-type or B-type (39% A-type; 50% B-type; 5% A- and B-type; 5% untypeable). These results indicated that DNA sequence heterogeneity within the EBNA2 gene region may exist in different strains of EBV. The extent of DNA sequence heterogeneity among different strains of EBV was determined by sequencing of a region within the EBNA2 gene in a number of different A-type and B-type strains of EBV originating from Africa or New Guinea. The results demonstrated DNA sequence heterogeneity within the EBNA2 gene in different strains of EBV. This heterogeneity was more extensive among A-type strains than B-type strains of EBV.

Africa↗
PubMed1994

Identification of a novel protein from adult chicken brain that inhibits neurite outgrowth.

Glycoproteins that inhibit neurite outgrowth may guide growth cones during development by acting as a barrier and closing off inappropriate routes. Their continued expression in the adult central nervous system may be a key factor in preventing regeneration of central nervous system neurons. A glycoprotein of 55 kDa has been isolated from the detergent-insoluble membrane skeleton from adult chicken brain. Initial experiments showed that dorsal root ganglion neurons would not adhere to or extend neurites on a substratum coated with GP55. Furthermore, GP55 will act as a barrier to the advance of established growth cones in the presence of poly-L-lysine, laminin or G4. Central nervous system neurons from forebrain as well as dorsal root ganglion neurons from the peripheral nervous system are inhibited by GP55. GP55 is also effective in blocking the initial adhesion of neurons to a substratum of poly-L-lysine and, particularly, laminin. In contrast to the inhibition of neurite outgrowth, neuronal adhesion is concentration independent over the range tested. A preliminary investigation of the mechanism by which GP55 inhibits outgrowth suggests that a pertussis toxin-sensitive G protein is required. Preliminary evidence suggests that GP55 is anchored in the membrane by a glycosyl phosphatidylinositol moiety. GP55 is distinct from previously identified inhibitory proteins, based on the source and molecular mass, and is thus a new member of this rapidly expanding family.

Animals↗
PubMed1993

Presentation of endogenous viral peptide epitopes by anti-CD40 stimulated human B cells following recombinant vaccinia infection.

Cytotoxic T lymphocytes (CTLs) recognising viral antigens are an important host defence mechanism in restricting the proliferation of virus-infected cells. Previously, lymphoblastoid cell lines (LCLs) infected with vaccinia recombinants encoding viral proteins have been used to identify specific CTL epitopes. However, to localise the EBV CTL epitopes encoded by Epstein-Barr virus (EBV) transformants, LCLs are an inappropriate host for vaccinia recombinants. In the present study, an alternative host cell for vaccinia infection is described. Initial studies demonstrated that anti-CD40 stimulated human B cells replicated vaccinia virus and expressed EBV nuclear antigen(s) (EBNA) following infection with recombinant vaccinia encoding the appropriate region of the EBV genome. Recombinant vaccinia-infected anti-CD40 stimulated B cell lines were then used to localise target epitopes for a panel of EBV-specific CTL clones. Most importantly, in vitro stimulation of unfractionated mononuclear cells with recombinant vaccinia-infected anti-CD40 B cells activated a memory CTL response. Based on the vaccinia results, screening of peptides from EBNA6 defined the epitope for the EBNA6-specific CTL clones to the sequence KEHVIQNAFRK. This work clearly demonstrates that anti-CD40 stimulated B cell lines not only provide an efficient tool for localising CTL epitopes but also presents an alternative mechanism of reactivating a memory T cell response to any gene product expressed by recombinant vaccinia.

Amino Acid Sequence↗
PubMed1993

EBV peptide epitope sensitization restores human cytotoxic T cell recognition of Burkitt's lymphoma cells. Evidence for a critical role for ICAM-2.

The pathogenesis of EBV+ Burkitt's lymphoma (BL) suggests evasion of the CTL response against EBV. Two important features of this tumor have been previously suggested to explain this immune evasion, (a) absence/low expression of cellular adhesion molecules and (b) restricted expression of EBV latent Ag. To determine the relative importance of these features in relation to evasion of EBV-specific CTL, a group of BL cell lines with variable expression of the aforementioned phenotypic characteristics were assayed for specific CTL lysis after exogenous addition of EBV peptide epitopes. In spite of down-regulated expression of the adhesion molecules LFA-1, LFA-3, and/or ICAM-1, peptide-sensitized BL cells were recognized and lysed by EBV-specific CTL. Moreover, there was no significant difference between the CTL lysis of the BL cells and that of adhesion molecule-positive control cells over a wide range of peptide epitope concentrations. Blocking experiments with mAb to individual adhesion molecules suggested that virus-specific CTL recognition of lymphoblastoid cell lines was dependent on an intact LFA-3/CD2 pathway. In contrast, the CTL recognition of peptide-sensitized BL cells was critically dependent on the LFA-1/ICAM pathway, with an insignificant contribution by CD2/LFA-3. The consistently high expression of ICAM-2 on all BL cell lines suggests that the accessory function in CTL recognition of these cells is mediated by the LFA-1/ICAM-2 pathway. Thus, down-regulation of LFA-1, LFA-3, and/or ICAM-1 expression on BL cells does not provide an absolute barrier to tumor cell recognition by virus-specific CTL. The ability of virus-specific CTL to recognize peptide epitope-sensitized BL cells as efficiently as normal cells has demonstrated the importance of latent Ag expression in the CTL control of EBV+ tumors.

Amino Acid Sequence↗
PubMed1993

Peptide epitope induced apoptosis of human cytotoxic T lymphocytes. Implications for peripheral T cell deletion and peptide vaccination.

Cloned CTL can be induced to undergo apoptosis with cognate peptide epitopes. This phenomenon has been attributed to self recognition and self destruction of individual, isolated CTL and/or Ag-induced cell death. It has been claimed that these mechanism are responsible for extrathymic elimination of primed CTL. In our study the contribution of all known effector mechanisms (single cell self killing, CTL-CTL killing, backward killing, bystander killing, Ag-induced cell death, and veto) to peptide epitope-induced destruction of CTL was evaluated. CTL-CTL killing was found to be the dominant mechanism, with a significant contribution from bystander killing. CTL were as susceptible to peptide-mediated lysis as conventional target cells. CTL, which were actively killing target cells, were not refractory to the lytic mechanisms of other CTL but paradoxically, avoid destruction by their own lytic mediators when delivering the lethal hit. These data imply that mature primed CTL are not deleted in the periphery as a direct result of the lysis of target cells, although, under certain circumstances peripheral CTL-CTL killing may be envisaged when cognate peptide is used for vaccination.

Amino Acid Sequence↗
PubMed1993

Spontaneous apoptosis in NS-1 myeloma cultures: effects of cell density, conditioned medium and acid pH.

Apoptosis is a form of cell death which plays an important role in many biological processes including the regulation of B and T lymphocyte functions. We report here the spontaneous development of extensive apoptosis in cultures of the NS-1 mouse myeloma cell line following overgrowth. The apoptosis was identified by both its ultrastructural features and its DNA fragmentation pattern. High cell density and conditioned medium, but not acid pH, were found to be major inducers of apoptosis in this experimental system.

Animals↗
PubMed1993

Sexually transmitted diseases in college men: a preliminary clinical investigation.

Continuing efforts to educate college students about the dangers of unprotected sexual intercourse have resulted in little evidence of positive change in sexual behavior. This clinical study examined the sexual behavior, perceived risk of human immunodeficiency virus, and pathology of 66 university men attending a health center's men's clinic for treatment of sexually transmitted disease (STD). The study demonstrated the existence of a high-risk group of men who, despite sexually transmitted disease pathology, high numbers of sexual partners, inconsistent condom use, and delays in seeking treatment, perceive their risk of contracting HIV/AIDS as being extremely low. This preliminary investigation suggests the need for specific education interventions and future in-depth studies of this population.

Adult↗
PubMed1993

Substrate-bound GP130/F11 will promote neurite outgrowth: evidence for a cell surface receptor.

GP130/F11 is a neuronal cell adhesion molecule belonging to the Ig superfamily. Preliminary evidence suggests that it may be important for the fasciculation of axons and cell-cell interactions during synaptogenesis. Previous work has shown that when F3 (the mouse homologue) is transfected into Chinese hamster ovary (CHO) cells it will act as a substrate for neuronal growth and adhesion. In this study we have shown that isolated GP130/F11 will also act as a substrate for the growth of chick dorsal root ganglia cell neurons. The concentration of GP130/F11 on the surface of sympathetic neurons, grown for one day in culture was approximately 40 ng cm-2 which was comparable to the levels required to stimulate neurite outgrowth. Deglycosylation of GP130/F11 or partial denaturation by boiling did not abolish the activity. However, after treatment with dithiothreitol, GP130/F11 was no longer capable of stimulating neurite outgrowth. GP130/F11 will also stimulate neurite outgrowth from forebrain neurons from 7 to 9-day-old embryos. These do not express GP130/F11 until around day 10, providing further evidence that GP130/F11 interacts with an as yet unknown cell surface receptor.

Animals↗