scholarly journals Both L3T4+ and Lyt-2+ helper T cells initiate cytotoxic T lymphocyte responses against allogenic major histocompatibility antigens but not against trinitrophenyl-modified self.

1985 ◽  
Vol 162 (2) ◽  
pp. 427-443 ◽  
Author(s):  
T Mizuochi ◽  
H Golding ◽  
A S Rosenberg ◽  
L H Glimcher ◽  
T R Malek ◽  
...  
Keyword(s):  
Cell Population ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Interleukin 2 ◽  
Class I ◽  
Major Histocompatibility ◽  
Th Cells ◽  
Th Cell ◽  
T Cell Subpopulations ◽  
Ctl Responses

This study characterizes the T helper (Th) cells that initiate primary cytotoxic T lymphocyte (CTL) responses against allogeneic and trinitrophenyl (TNP)-modified self class I major histocompatibility (MHC) determinants. We show that two distinct Th cell subsets participate in allospecific CTL responses: (a) an L3T4+,Lyt-2- class II-restricted Th cell population, and (b) an L3T4-,Lyt-2+ class I-restricted Th cell population. Both of these T cell subpopulations were shown to function in allospecific CTL responses as helper cells by their ability to show synergy with allospecific CTL precursors. Thus, primary class I allospecific CTL responses represent an immune response involving not only L3T4+ Th cells, but Lyt-2+ Th cells as well. One of the necessary functions performed by both L3T4+ and Lyt-2+ Th cell populations in allospecific CTL responses was found to be the secretion of interleukin 2. Finally, despite the many similarities between anti-allo- and anti-TNP-CTL responses, anti-TNP-CTL responses were found to be mediated by only L3T4+ Th cells, not by Lyt-2+ Th cells. Consequently, Lyt-2+ Th cells appear to be a helper cell population that is primarily involved in MHC-specific immune responses.

scholarly journals Escape in One of Two Cytotoxic T-Lymphocyte Epitopes Bound by a High-Frequency Major Histocompatibility Complex Class I Molecule, Mamu-A*02: a Paradigm for Virus Evolution and Persistence?

2002 ◽  
Vol 76 (22) ◽  
pp. 11623-11636 ◽  
Author(s):  
Thorsten U. Vogel ◽  
Thomas C. Friedrich ◽  
David H. O'Connor ◽  
William Rehrauer ◽  
Elizabeth J. Dodds ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Mhc Class I ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Class I ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Mhc Class I Molecule ◽  
Immunodeficiency Virus ◽  
Ctl Responses

ABSTRACT It is now accepted that an effective vaccine against AIDS must include effective cytotoxic-T-lymphocyte (CTL) responses. The simian immunodeficiency virus (SIV)-infected rhesus macaque is the best available animal model for AIDS, but analysis of macaque CTL responses has hitherto focused mainly on epitopes bound by a single major histocompatibility complex (MHC) class I molecule, Mamu-A*01. The availability of Mamu-A*01-positive macaques for vaccine studies is therefore severely limited. Furthermore, it is becoming clear that different CTL responses are able to control immunodeficiency virus replication with varying success, making it a priority to identify and analyze CTL responses restricted by common MHC class I molecules other than Mamu-A*01. Here we describe two novel epitopes derived from SIV, one from Gag (Gag71-79 GY9), and one from the Nef protein (Nef159-167 YY9). Both epitopes are bound by the common macaque MHC class I molecule, Mamu-A*02. The sequences of these two eptiopes are consistent with the molecule's peptide-binding motif, which we have defined by elution of natural ligands from Mamu-A*02. Strikingly, we found evidence for the selection of escape variant viruses by CTL specific for Nef159-167 YY9 in 6 of 6 Mamu-A*02-positive animals. In contrast, viral sequences encoding the Gag71-79 GY9 epitope remained intact in each animal. This situation is reminiscent of Mamu-A*01-restricted CTL that recognize Tat28-35 SL8, which reproducibly selects for escape variants during acute infection, and Gag181-189 CM9, which does not. Differential selection by CTL may therefore be a paradigm of immunodeficiency virus infection.

scholarly journals B7 Costimulation Is Critical for Antibody Class Switching and CD8+ Cytotoxic T-Lymphocyte Generation in the Host Response to Vesicular Stomatitis Virus

2000 ◽  
Vol 74 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Alexander J. McAdam ◽  
Evan A. Farkash ◽  
Benjamin E. Gewurz ◽  
Arlene H. Sharpe
Keyword(s):  
Viral Infection ◽  
Vesicular Stomatitis Virus ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Class I ◽  
Specific Class ◽  
Wild Type ◽  
B7 Molecules ◽  
Vesicular Stomatitis ◽  
Ctl Responses

ABSTRACT Antibody and cytotoxic T-lymphocyte (CTL) responses have critical roles in eliminating many viral infections. In addition to stimulation of the T-cell receptor, T cells require costimulatory signals to respond optimally. We evaluated the role of B7 costimulatory molecules (B7-1 and B7-2) in the immune response to viral infection using vesicular stomatitis virus (VSV) and mice lacking either B7-1 or B7-2 or both molecules. Mice lacking both B7-1 and B7-2 had essentially no anti-VSV immunoglobulin G1 (IgG1) response, decreased IgG2a responses, and normal IgM responses, while mice lacking either B7-1 or B7-2 had unaltered anti-VSV antibody responses compared to wild-type mice. Depletion of CD4+ cells further reduced the IgG2a response in mice lacking both B7 molecules, suggesting that CD4−cells may supply help for IgG2a in the absence of B7 costimulation. The absence of both B7 molecules profoundly reduced generation of both primary and secondary VSV-specific class I major histocompatibility complex (MHC)-restricted CTL, whereas VSV-specific CTL responses in mice lacking either B7-1 or B7-2 were similar to those of wild-type animals. Class I MHC-restricted CTL in wild-type mice were not dependent on CD4+ cells, suggesting that the failure of CTL in the absence of B7s is due to a lack of B7 costimulation directly to the CD8+ CTL. These data demonstrate that B7-1 and B7-2 have critical, overlapping functions in the antibody and CTL responses to this viral infection.

scholarly journals T-T cell interactions during in vitro cytotoxic T lymphocyte responses. V. Precursor frequencies and specificity of alloreactive helper T cells.

1982 ◽  
Vol 156 (1) ◽  
pp. 41-54 ◽  
Author(s):  
M Krönke ◽  
P Scheurich ◽  
K Pfizenmaier ◽  
M Röllinghoff ◽  
H Wagner
Keyword(s):  
T Cell ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Interleukin 2 ◽  
Third Party ◽  
Antigen Specificity ◽  
Murine Spleen ◽  
Helper Activity ◽  
Ctl Responses

We assessed the quantitative representation and specificity of alloreactive helper T lymphocytes (HTL) within murine spleen cells by three different limiting dilution systems. For the induction of primary cytolytic T lymphocyte (CTL) responses towards alloantigens, a Lyt-1+23- HTL precursor (HTLp) could be defined, which occurred at frequencies of 1/2.000-1/50,000, depending on the alloantigen in question. The HTLp limiting for interleukin-2 (Il-2) production also expressed the Lyt-1+ phenotype and occurred in similar frequencies. This cell type was concluded to be the limiting HTLp for the overall helper activity required for the induction of primary CTL responses. HTLp reactive to Mlsa -encoded antigens occurred at higher frequencies (1/500) than those reactive towards whole allogeneic H-2 haplotypes (1/4,000-1/7,000). Within the H-2 complex, I region-encoded alloantigens activated approximately 10 times more HTLp than did H-2K or H-2D regions. When alloreactive HTL were tested for antigen specificity at the clonal level, approximately 80% of the HTL clones proved to be specific to the alloantigen used for immunization, whereas approximately 20% reacted also towards third-party alloantigens. The data are discussed with respect to putative T-T interactions within the helper T cell population and the precision of alloantigen recognition by HTL.

scholarly journals Decrypting the structure of major histocompatibility complex class I-restricted cytotoxic T lymphocyte epitopes with complex peptide libraries.

1995 ◽  
Vol 181 (6) ◽  
pp. 2097-2108 ◽  
Author(s):  
K Udaka ◽  
K H Wiesmüller ◽  
S Kienle ◽  
G Jung ◽  
P Walden
Keyword(s):  
Amino Acids ◽  
Major Histocompatibility Complex ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Peptide Libraries ◽  
Class I ◽  
Major Histocompatibility ◽  
Mhc Molecules ◽  
Histocompatibility Complex ◽  
The Individual

Complex synthetic peptide libraries with defined amino acids in one or more positions of the H-2Kb-restricted cytotoxic T lymphocyte (CTL) epitopes SIINFEKL and RGYVYQGL and mixtures of 19 amino acids in the remaining positions were used to analyze the structural requirements of peptide binding to MHC class I molecules and antigen recognition by CTLs. This approach provides means to assess semiquantitatively the contribution of every amino acid to the binding of peptides to major histocompatibility complex (MHC) molecules without biases introduced by naturally processed peptides. Primary and secondary anchor residues were defined for their major contribution to the binding efficiency of the peptides. In contrast to primary anchors, secondary anchor amino acids vary greatly in their side chains and position in the sequences. All amino acids in the octapeptide sequences were found to exhibit positive or negative influences on binding to the MHC molecules and on recognition of the resulting complexes by CTLs. Strong interdependence of the effects of the individual residues in the epitope sequences was demonstrated. CTL responses to peptide libraries were suppressed when residues were introduced; however, they were augmented when the critical residues for T cell recognition were fixed, suggesting a potential use of the peptide libraries for defining epitope sequences in general.

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