scholarly journals Enhanced immune activity of cytotoxic T-lymphocyte epitope analogs derived from positional scanning synthetic combinatorial libraries

Blood ◽  
2001 ◽  
Vol 97 (6) ◽  
pp. 1776-1786 ◽  
Author(s):  
Corinna La Rosa ◽  
Radhika Krishnan ◽  
Susan Markel ◽  
Jonathan P. Schneck ◽  
Richard Houghten ◽  
...  
Keyword(s):  
T Cell ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Combinatorial Libraries ◽  
Peptide Sequence ◽  
Ctl Epitopes ◽  
Ctl Epitope ◽  
Positional Scanning ◽  
Synthetic Combinatorial Libraries

The pp65495-503 cytotoxic T-lymphocyte (CTL) epitope from cytomegalovirus (CMV) is universally recognized among CMV+ individuals who express an allele of the human leukocyte antigen A (HLA-A*0201). The relative binding affinity of the epitope to HLA-A*0201 is moderate, and its increased activity might prove beneficial in its use as a CTL epitope vaccine. A new approach to enhance the activity of T-cell epitopes is the use of positional scanning synthetic combinatorial libraries (PS-SCLs). Using a nonamer PS-SCL, the pp65495-503 epitope was modified after screening a CMV-specific T-cell clone (TCC) (3-3F4) from which the native peptide sequence was derived. Two peptides with amino acid substitutions at P1, P3, P7, and P8 are between 103 and 104 more active than the native epitope. Although the native CTL epitope terminates as a free acid, both tetrasubstituted peptides only function as CTL epitopes when the carboxyl terminus is amidated. Selective substitution of the native sequence based on PS-SCL screening results identified 3 amidated monosubstituted and disubstituted peptides that are better recognized than the native epitope by TCCs from a cohort expressing HLA-A*0201. In vitro stimulation of peripheral blood mononuclear cells with each of the peptide epitope analogs stimulated memory CTLs, which recognized CMV-infected targets among a high percentage of CMV+ individuals. Binding studies of peptide analogs with HLA-Ig (immunoglobulin) dimers and 2 different TCCs correlated with in vitro lysis results. These data suggest that increasing the activity of CTL epitopes while maintaining broad recognition is possible, which holds promise for vaccine development in infectious disease and cancer.

scholarly journals A Subdominant CD8+ Cytotoxic T Lymphocyte (CTL) Epitope from the Plasmodium yoeliiCircumsporozoite Protein Induces CTLs That Eliminate Infected Hepatocytes from Culture

2000 ◽  
Vol 68 (6) ◽  
pp. 3403-3411 ◽  
Author(s):  
Eileen D. Franke ◽  
Alessandro Sette ◽  
John Sacci ◽  
Scott Southwood ◽  
Giampietro Corradin ◽  
...  
Keyword(s):  
T Cell ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Plasmodium Yoelii ◽  
Binding Motif ◽  
Dna Encoding ◽  
Ctl Response ◽  
Ctl Epitope ◽  
Multiple Antigen Peptide

ABSTRACT Previous studies indicated that the Plasmodium yoeliicircumsporozoite protein (PyCSP) 57–70 region elicits T cells capable of eliminating infected hepatocytes in vitro. Herein, we report that the PyCSP58–67 sequence contains an H-2d binding motif, which binds purified Kd molecules in vitro with low affinity (3,267 nM) and encodes an H-2d-restricted cytotoxic T lymphocyte (CTL) epitope. Immunization of BALB/c mice with three doses of a multiple antigen peptide (MAP) construct containing four branches of amino acids 57 to 70 linked to a lysine-glycine core [MAP4(PyCSP57–70)] and Lipofectin as the adjuvant induced both T-cell proliferation and a peptide-specific CTL response that was PyCSP59–67 specific, H-2d restricted, and CD8+T cell dependent. Immunization with either DNA encoding the PyCSP or irradiated sporozoites demonstrated that this CTL epitope is subdominant since it is not recognized in the context of whole CSP immunization. The biological relevance of this CTL response was underlined by the demonstration that it could mediate genetically restricted, CD8+- and nitric-oxide-dependent elimination of infected hepatocytes in vitro, as well as partial protection of BALB/c mice against sporozoite challenge. These findings indicate that subdominant epitopes with low major histocompatibility complex affinity can be used to engineer epitope-based vaccines and have implications for the selection of epitopes for subunit-based vaccines.

scholarly journals Efficient Identification of Novel Hla-A*0201–Presented Cytotoxic T Lymphocyte Epitopes in the Widely Expressed Tumor Antigen Prame by Proteasome-Mediated Digestion Analysis

2001 ◽  
Vol 193 (1) ◽  
pp. 73-88 ◽  
Author(s):  
Jan H. Kessler ◽  
Nico J. Beekman ◽  
Sandra A. Bres-Vloemans ◽  
Pauline Verdijk ◽  
Peter A. van Veelen ◽  
...  
Keyword(s):  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Epitope Prediction ◽  
Binding Prediction ◽  
Ctl Epitopes ◽  
High Affinity ◽  
Tumor Associated Antigen ◽  
Immunotherapy Of Cancer ◽  
Binding Peptides

We report the efficient identification of four human histocompatibility leukocyte antigen (HLA)-A*0201–presented cytotoxic T lymphocyte (CTL) epitopes in the tumor-associated antigen PRAME using an improved “reverse immunology” strategy. Next to motif-based HLA-A*0201 binding prediction and actual binding and stability assays, analysis of in vitro proteasome-mediated digestions of polypeptides encompassing candidate epitopes was incorporated in the epitope prediction procedure. Proteasome cleavage pattern analysis, in particular determination of correct COOH-terminal cleavage of the putative epitope, allows a far more accurate and selective prediction of CTL epitopes. Only 4 of 19 high affinity HLA-A*0201 binding peptides (21%) were found to be efficiently generated by the proteasome in vitro. This approach avoids laborious CTL response inductions against high affinity binding peptides that are not processed and limits the number of peptides to be assayed for binding. CTL clones induced against the four identified epitopes (VLDGLDVLL, PRA100–108; SLYSFPEPEA, PRA142–151; ALYVDSLFFL, PRA300–309; and SLLQHLIGL, PRA425–433) lysed melanoma, renal cell carcinoma, lung carcinoma, and mammary carcinoma cell lines expressing PRAME and HLA-A*0201. This indicates that these epitopes are expressed on cancer cells of diverse histologic origin, making them attractive targets for immunotherapy of cancer.

scholarly journals Cytotoxic T-Lymphocyte Epitope Vaccination Protects against Human Metapneumovirus Infection and Disease in Mice

2006 ◽  
Vol 80 (4) ◽  
pp. 2034-2044 ◽  
Author(s):  
Karen A. Herd ◽  
Suresh Mahalingam ◽  
Ian M. Mackay ◽  
Michael Nissen ◽  
Theo P. Sloots ◽  
...  
Keyword(s):  
Young Children ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Human Metapneumovirus ◽  
Respiratory Pathogen ◽  
Interleukin 12 ◽  
Ctl Epitopes ◽  
Ctl Epitope ◽  
Hmpv Infection ◽  
Tract Infections

ABSTRACT Human metapneumovirus (hMPV) has emerged as an important human respiratory pathogen causing upper and lower respiratory tract infections in young children and older adults. In addition, hMPV infection is associated with asthma exacerbation in young children. Recent epidemiological evidence indicates that hMPV may cocirculate with human respiratory syncytial virus (hRSV) and mediate clinical disease similar to that seen with hRSV. Therefore, a vaccine for hMPV is highly desirable. In the present study, we used predictive bioinformatics, peptide immunization, and functional T-cell assays to define hMPV cytotoxic T-lymphocyte (CTL) epitopes recognized by mouse T cells restricted through several major histocompatibility complex class I alleles, including HLA-A*0201. We demonstrate that peptide immunization with hMPV CTL epitopes reduces viral load and immunopathology in the lungs of hMPV-challenged mice and enhances the expression of Th1-type cytokines (gamma interferon and interleukin-12 [IL-12]) in lungs and regional lymph nodes. In addition, we show that levels of Th2-type cytokines (IL-10 and IL-4) are significantly lower in hMPV CTL epitope-vaccinated mice challenged with hMPV. These results demonstrate for the first time the efficacy of an hMPV CTL epitope vaccine in the control of hMPV infection in a murine model.

scholarly journals Consistent Cytotoxic-T-Lymphocyte Targeting of Immunodominant Regions in Human Immunodeficiency Virus across Multiple Ethnicities

2004 ◽  
Vol 78 (5) ◽  
pp. 2187-2200 ◽  
Author(s):  
Nicole Frahm ◽  
B. T. Korber ◽  
C. M. Adams ◽  
J. J. Szinger ◽  
R. Draenert ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
T Cell Responses ◽  
Peptide Sequence ◽  
Immune Recognition ◽  
Cell Responses ◽  
Clade B ◽  
Immunodeficiency Virus

ABSTRACT Although there is increasing evidence that virus-specific cytotoxic-T-lymphocyte (CTL) responses play an important role in the control of human immunodeficiency virus (HIV) replication in vivo, only scarce CTL data are available for the ethnic populations currently most affected by the epidemic. In this study, we examined the CD8+-T-cell responses in African-American, Caucasian, Hispanic, and Caribbean populations in which clade B virus dominates and analyzed the potential factors influencing immune recognition. Total HIV-specific CD8+-T-cell responses were determined by enzyme-linked immunospot assays in 150 HIV-infected individuals by using a clade B consensus sequence peptide set spanning all HIV proteins. A total of 88% of the 410 tested peptides were recognized, and Nef- and Gag-specific responses dominated the total response for each ethnicity in terms of both breadth and magnitude. Three dominantly targeted regions within these proteins that were recognized by >90% of individuals in each ethnicity were identified. Overall, the total breadth and magnitude of CD8+-T-cell responses correlated with individuals' CD4 counts but not with viral loads. The frequency of recognition for each peptide was highly correlated with the relative conservation of the peptide sequence, the presence of predicted immunoproteasomal cleavage sites within the C-terminal half of the peptide, and a reduced frequency of amino acids that impair binding of optimal epitopes to the restricting class I molecules. The present study thus identifies factors that contribute to the immunogenicity of these highly targeted and relatively conserved sequences in HIV that may represent promising vaccine candidates for ethnically heterogeneous populations.

scholarly journals Cytotoxic T Lymphocyte–associated Antigen 4 (CTLA-4) Can Regulate Dendritic Cell–induced Activation and Cytotoxicity of CD8+ T Cells Independently of CD4+T Cell Help

1999 ◽  
Vol 189 (7) ◽  
pp. 1157-1162 ◽  
Author(s):  
Kathy D. McCoy ◽  
Ian F. Hermans ◽  
J. Henry Fraser ◽  
Graham Le Gros ◽  
Franca Ronchese
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocyte ◽  
Cd8 T Cells ◽  
Cytotoxic T Lymphocyte ◽  
Cd4 T Cell ◽  
Cd4 T Cell Help ◽  
T Cell Help

The mechanisms that regulate the strength and duration of CD8+ cytotoxic T cell activity determine the effectiveness of an antitumor immune response. To better understand the antitumor effects of anti-cytotoxic T lymphocyte–associated antigen 4 (CTLA-4) antibody treatment, we analyzed the effect of CTLA-4 signaling on CD8+ T cells in vitro and in vivo. In vitro, cross-linking of CTLA-4 on purified CD8+ T cells caused decreased proliferative responses to anti-CD3 stimulation and rapid loss of activation marker expression. In vivo, blockade of CTLA-4 by neutralizing anti–CTLA-4 mAb greatly enhanced the accumulation, activation, and cytotoxic activity of CD8+ T cells induced by immunization with Ag on dendritic cells (DC). This enhanced response did not require the expression of MHC class II molecules on DC or the presence of CD4+ T cells. These results demonstrate that CTLA-4 blockade is able to directly enhance the proliferation and activation of specific CD8+ T cells, indicating its potential for tumor immunotherapy even in situations in which CD4+ T cell help is limited or absent.

scholarly journals Assessment of the extent of variation in influenza A virus cytotoxic T-lymphocyte epitopes by using virus-specific CD8+ T-cell clones

2007 ◽  
Vol 88 (2) ◽  
pp. 530-535 ◽  
Author(s):  
E. G. M. Berkhoff ◽  
M. M. Geelhoed-Mieras ◽  
R. A. M. Fouchier ◽  
A. D. M. E. Osterhaus ◽  
G. F. Rimmelzwaan
Keyword(s):  
T Cell ◽  
Influenza A Virus ◽  
T Lymphocyte ◽  
Influenza A ◽  
Matrix Protein ◽  
Cytotoxic T Lymphocyte ◽  
H3n2 Virus ◽  
Human Virus ◽  
Ctl Epitopes ◽  
Cell Clones

The influenza A virus nucleoprotein (NP) and matrix protein are major targets for human virus-specific cytotoxic T-lymphocyte (CTL) responses. Most of the CTL epitopes that have been identified so far are conserved. However, sequence variation in CTL epitopes of the NP has recently been demonstrated to be associated with escape from virus-specific CTLs. To assess the extent of variation in CTL epitopes during influenza A virus evolution, 304 CTL clones derived from six study subjects were obtained with specificity for an influenza A/H3N2 virus isolated in 1981. Subsequently, the frequency of the CTL clones that failed to recognize a more recent influenza virus strain isolated in 2003 was determined. In four of six study subjects, CTLs were found to be specific for variable epitopes, accounting for 2.6 % of all CTL clones. For some of these CTL clones, the minimal epitope and the residues responsible for abrogation of T-cell recognition were identified.

scholarly journals Glycan-regulated Antigen Processing of a Protein in the Endoplasmic Reticulum Can Uncover Cryptic Cytotoxic T Cell Epitopes

1998 ◽  
Vol 188 (4) ◽  
pp. 773-778 ◽  
Author(s):  
Philip Wood ◽  
Tim Elliott
Keyword(s):  
Endoplasmic Reticulum ◽  
T Cell ◽  
T Lymphocyte ◽  
Influenza A ◽  
Antigen Processing ◽  
Secretory Pathway ◽  
Cytotoxic T Lymphocyte ◽  
Cytotoxic T Cell ◽  
T Cell Epitopes ◽  
Ctl Epitopes

We and others have shown that influenza A nucleoprotein (NP) targeted to the secretory pathway cannot be processed to yield several cytotoxic T lymphocyte (CTL) epitopes in cell lines that lack the transporter associated with antigen processing (TAP). However, a large COOH-terminal fragment of NP is processed and presented in these cells. Full-length NP is cotranslationally glycosylated in the lumen of the endoplasmic reticulum at two sites distal to the major H2-Kk and H2-Db restricted CTL epitopes, and we show here that pharmacological or genetic inhibition of N-linked glycosylation, leads to the processing and presentation of both these epitopes in a TAP-independent way.

scholarly journals Cellular and genetic restrictions in the immunoregulatory activity of alpha-fetoprotein. II. Alpha-fetoprotein-induced suppression of cytotoxic T lymphocyte development.

1978 ◽  
Vol 148 (2) ◽  
pp. 360-372 ◽  
Author(s):  
A B Peck ◽  
R A Murgita ◽  
H Wigzell
Keyword(s):  
T Cell ◽  
Cytotoxic T Lymphocytes ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Alpha Fetoprotein ◽  
Immunosuppressive Activity ◽  
Primary Target ◽  
Histocompatibility Complex ◽  
Activation Phase

Alpha-fetoprotein (AFP), a major component of fetal and newborn sera, was shown to exert significant immunosuppressive activity on the in vitro generation of cytotoxic T lymphocytes (CTLs). This suppression proved independent of the suppressibility of the mixed leukocyte culture activation phase, since strain combinations whose proliferative responses were refractive to AFP-induced suppression also failed to develop demonstrable CTLs in the presence of AFP. Several strain combinations were also found in which normal generation of CTLs occurred in cultures containing AFP. This refractive nature correlated with the presence of nonsuppressible lymphocyte-stimulating alloantigenic systems on the stimulating cell population. These data provide the basis for proposing several possible mechanisms for AFP-induced suppression of T-cell-mediated cytotoxicity, as well as suggesting that the primary target of this suppression is the proliferating helper T cell precommited to respond towards the major histocompatibility complex-associated lymphocyte-activating determinants.

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