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C D Pendleton

Publications and source records attributed to C D Pendleton.

26 records · Page 2Linked to original sources
PubMed1992

Serum angiotensin-1 converting enzyme activity processes a human immunodeficiency virus 1 gp160 peptide for presentation by major histocompatibility complex class I molecules.

T cell stimulation by the human immunodeficiency virus 1 gp160-derived peptide p18 presented by H-2Dd class I major histocompatibility complex molecules in a cell-free system was found to require proteolytic cleavage. This extracellular processing was mediated by peptidases present in fetal calf serum. In vitro processing of p18 resulted in a distinct reverse phase high performance liquid chromatography profile, from which a biologically active product was isolated and sequenced. This peptide processing can be specifically blocked by the angiotensin-1 converting enzyme (ACE) inhibitor captopril, and can occur by exposing p18 to purified ACE. The ability of naturally occurring extracellular proteases to convert inactive peptides to T cell antigens has important implications for understanding cytotoxic T lymphocyte responses in vivo, and for rational peptide vaccine design.

Amino Acid Sequence↗
PubMed1992

Broad recognition of cytotoxic T cell epitopes from the HIV-1 envelope protein with multiple class I histocompatibility molecules.

A few cases have been described of antigenic determinants that are broadly presented by multiple class II MHC molecules, especially murine I-E or human DR, in which polymorphism is limited to the beta chain, and the alpha chain is conserved. However, no similar cases have been studied for presentation by class I MHC molecules. Because both domains of the MHC peptide binding site are polymorphic in class I molecules, exploring permissiveness in class I presentation would be of interest, and also such broadly presented antigenic determinants would clearly be useful for vaccine development. We had defined an immunodominant determinant, P18, of the HIV-1 gp160 envelope protein recognized by human and murine CTL. To determine the range of class I MHC molecules that could present this peptide and to determine whether two HIV-1 gp160 Th cell determinants, T1 and HP53, could also be presented by class I MHC molecules, we attempted to generate CTL specific for these three peptides in 10 strains of B10 congenic mice, representing 10 MHC types, and BALB/c mice. P18 was presented by at least four different class I MHC molecules from independent haplotypes (H-2d, p, u, and q to CD8+ CTL. In H-2d and H-2q the presentation was mapped to the D-end class I molecule, and for Dd, a requirement for both the alpha 1 and alpha 2 domains of Dd, not Ld, was found. HP53 was also presented by the same four different class I MHC molecules to CD8+ CTL although at higher concentrations. T1 was presented by class I molecules in three different strains of distinct MHC types (B10.M, H-2f; B10.A, H-2a; and B10, H-2b) to CTL. The CTL specific for P18 and HP53 were shown to be CD8+ and CD4- and to kill targets expressing endogenously synthesized whole gp160 as well as targets pulsed with the corresponding peptide. To compare the site within each peptide presented by the different class I molecules, we used overlapping and substituted peptides and found that the critical regions of each peptide are the similar for all four MHC molecules. Thus, antigenic sites are broadly or permissively presented by class I MHC molecules even without a nonpolymorphic domain as found in DR and I-E, and these sequences may be of broad usefulness in a synthetic vaccine.

Amino Acid Sequence↗
PubMed1992

Induction of broadly cross-reactive cytotoxic T cells recognizing an HIV-1 envelope determinant.

An immunodominant determinant for cytotoxic T lymphocytes (CTLs) exists in the hypervariable portion of human immunodeficiency virus-1 (HIV-1) gp160. Three mouse CTL lines (specific for isolates MN, RF, and IIIB) were examined for recognition of homologous determinants from distinct isolates. Only MN-elicited CTLs showed extensive interisolate cross-reactivity. Residue 325 played a critical role in specificity, with MN-elicited CTLs responding to peptides with an aromatic or cyclic residue and IIIB-induced cells recognizing peptides with an aliphatic residue at this position. CTL populations with broad specificities were generated by restimulation of IIIB-gp160 primed cells with MN-type peptides that have an aliphatic substitution at 325. This represents an approach to synthetic vaccines that can generate broadly cross-reactive CTLs capable of effector function against a wide range of HIV isolates.

AIDS Vaccines↗
PubMed1992

Induction of cytotoxic T cells to a cross-reactive epitope in the hepatitis C virus nonstructural RNA polymerase-like protein.

Cytotoxic T lymphocytes (CTL) have been found to mediate protection in vivo against certain virus infections. CTL also may play an important role in control of infection by hepatitis C virus (HCV), but no CTL epitopes have yet been defined in any HCV protein. The nonstructural protein with homology to RNA polymerase should be a relatively conserved target protein for CTL. To investigate the epitope specificity of CTL specific for this protein, we used 28 peptides from this sequence to study murine CTL. Mice were immunized with a recombinant vaccinia virus expressing the HCV nonstructural region corresponding to the flavivirus NS5 gene (RNA polymerase), and the primed spleen cells were restimulated in vitro with peptides. CTL from H-2d mice responded to a single 16-residue synthetic peptide (HCV 2422 to 2437). This relatively conserved epitope was presented by H-2d class I major histocompatibility complex (MHC) molecules to conventional CD4- CD8+ CTL but was not recognized by CTL restricted by H-2b. Moreover, exon shuffle experiments using several transfectants expressing recombinant Dd/Ld and Kd demonstrated that this peptide is seen in association with alpha 1 and alpha 2 domains of the Dd class I MHC molecule. This peptide differs from the homologous segments of this nonstructural region from three other HCV isolates by one residue each. Variant peptides with single amino acid substitutions were made to test the effect of each residue on the ability to sensitize targets. Neither substitution affected recognition. Therefore, these conservative mutations affected peptide interaction neither with the Dd class I MHC molecule nor with the T-cell receptor. Because these CTL cross-react with all four sequenced isolates of HCV in the United States and Japan, if human CTL display similar cross-reactivity, this peptide may be valuable for studies of HCV diagnosis and vaccine development. Our study provides the first evidence that CD8+ CTL can recognize an epitope from the HCV sequence in association with a class I MHC molecule.

Amino Acid Sequence↗
PubMed1991

Construction of peptides encompassing multideterminant clusters of human immunodeficiency virus envelope to induce in vitro T cell responses in mice and humans of multiple MHC types.

To make synthetic peptide vaccines effective in a broad population of outbred humans, one would have to incorporate enough antigenic determinants to elicit recognition by T cells of most HLA types. We have previously defined multideterminant regions of the human immunodeficiency virus (HIV) envelope that include overlapping determinants seen by proliferating T cells of three or four haplotypes of mice. We have now tested the hypothesis that synthetic peptides encompassing such multideterminant regions will be recognized by T cells of multiple murine MHC types as well as by human T cells representing multiple HLA types. Six such peptides of 20-33 residues in length were prepared, and tested for their ability to stimulate T cells from mice of four distinct MHC types immunized with recombinant envelope protein rgp 160, as well as from 42 HIV-infected humans of different HLA types. Results identify several such peptides that are broadly recognized by mice of four H-2 types and by 52-73% of infected humans who still retain IL-2 productive responses to control recall antigens such as influenza A virus or tetanus toxoid. 86% of such infected donors tested against at least three peptides respond to at least one of the six peptides, and 77% of an additional group of seropositives respond to a mixture of the peptides. Moreover, the peptides can be used to immunize mice to elicit T cells reactive with the intact HIV envelope protein. These peptides therefore may be useful for both vaccine development in the broad human population, and diagnostic or prognostic use.

Animals↗
PubMed1990

Characterization of a helper T cell epitope recognized by mice of a low responder major histocompatibility type.

Most known helper T cell (Th) epitopes studied have naturally been immunodominant epitopes recognized by T cells from animals of high responder major histocompatibility complex (MHC) haplotype. We have previously found that most such immunodominant Th epitopes tend to be amphipathic alpha helices, that is, helices with hydrophobic residues on one side and hydrophilic residues on the other, and the corresponding peptide can usually elicit a response to the native protein. However, very few epitopes seen by MHC low responder T cells have been identified. Within the CNBr fragment of residues 1-55 of sperm whale myoglobin (SwMb), a Th epitope is known to exist that stimulates T cells from low responder H-2k mice, but it has not yet been localized to a length of 8-12 residues, the usual length of a Th epitope. To determine whether this low responder epitope would have similar properties, we located it using 10 evenly overlapping 15-residue peptides that span the region. Analysis of this region by the computer program predicted the site covered by two peptides (residues 26-40 and 31-45 which overlap by 10 residues) to be the most likely site for a Th epitope. Of the 10 peptides tested experimentally, only one peptide (residues 26-40) was able to stimulate two low responder Th clones that are specific for the 1-55 region. The peptide was able to prime T cells of low responder B10.BR mice in vivo for in vitro response to the native SwMb as well as to the peptide fragment of residues 1-55. Immunization of low responder mice with SwMb showed that, of the 10 overlapping peptides, the major site of response within the 1-55 region is to the identified peptide. Finally, an extended peptide of residues 24-42 was made to increase the amphipathic score. This extended peptide induced greater proliferation of the clones. Thus, this low responder epitope has properties similar to those of immunodominant epitopes recognized by high responders.

Algorithms↗
PubMed1990

An epitope in human immunodeficiency virus 1 reverse transcriptase recognized by both mouse and human cytotoxic T lymphocytes.

T-cell-mediated cytotoxicity may play an important role in control of infection by the human immunodeficiency virus (HIV). In this study, we have identified and characterized a relatively conserved epitope in the HIV-1 reverse transcriptase recognized by murine and human cytotoxic T cells. This epitope was identified using a murine antigen-specific CD8+ class I major histocompatibility complex-restricted cytotoxic T-cell (CTL) line, a transfected fibroblast cell line expressing the HIV-1 pol gene, recombinant vaccinia viruses containing different truncated versions of the pol gene, and overlapping synthetic peptides. The optimal antigenic site was identified as residues 203-219 by synthesizing extended or truncated peptide analogs of the antigenic fragment. The optimal peptide was then tested for sensitization of autologous Epstein-Barr virus-transformed B-cell targets for killing by fresh human peripheral blood mononuclear cells. It was recognized by CTLs from several HIV-seropositive patients but not from any seronegative donor. Therefore, this peptide is a good candidate for inclusion in an AIDS vaccine. This study demonstrates that the same CTL epitope can be seen by murine and human CD8+ CTLs, as previously demonstrated for epitopes recognized by CD4+ helper T cells, and suggests the utility of screening for immunodominant CTL epitopes in mice prior to carrying out studies in humans.

Acquired Immunodeficiency Syndrome↗