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H J Stauss

Publications and source records attributed to H J Stauss.

At least 37 records · Page 2Linked to original sources
PubMed1996

Peptide-specific cytotoxic T lymphocytes restricted by nonself major histocompatibility complex class I molecules: reagents for tumor immunotherapy.

Studies in melanoma patients have revealed that self proteins can function as targets for tumor-reactive cytotoxic T lymphocytes (CTL). One group of self proteins MAGE, BAGE, and GAGE are normally only expressed in testis and placenta, whilst another group of CTL recognized proteins are melanocyte-specific differentiation antigens. In this study we have investigated whether CTL can be raised against a ubiquitously expressed self protein, mdm-2, which is frequently overexpressed in tumors. The observation that T-cell tolerance is self major histocompatibility complex-restricted was exploited to generate CTL specific for an mdm-2 derived peptide presented by nonself major histocompatibility complex class I molecules. Thus, the allo-restricted T-cell repertoire of H-2d mice was used to isolate CTL specific for the mdm100 peptide presented by allogeneic H-2Kb class I molecules. In vitro, these CTL discriminated between transformed and normal cells, killing specifically Kb-positive melanoma and lymphoma tumors but not Kb-expressing dendritic cells. In vivo, the CTL showed antitumor activity and delayed the growth of melanoma as well as lymphoma tumors in H-2b recipient mice. These experiments show that it is possible to circumvent T-cell tolerance to ubiquitously expressed self antigens, and to target CTL responses against tumors expressing elevated levels of structurally unaltered proteins.

Amino Acid Sequence↗
PubMed1996

A synthetic peptide derived from the tumor-associated protein mdm2 can stimulate autoreactive, high avidity cytotoxic T lymphocytes that recognize naturally processed protein.

Studies in melanoma patients have shown that unaltered self proteins can function as targets for tumor-reactive CTL. Here, we have investigated in a murine model whether autoreactive CTL can be found against the widely expressed proteins cyclin D1, mdm2, and p53, which are frequently overexpressed in transformed cells. Sixteen MHC class I binding peptides were identified in these proteins, and seven of them consistently stimulated primary CTL in vitro. Avidity measurements revealed that the avidity of peptide-induced CTL differed by >1000-fold. The highest avidity CTL were induced by a peptide derived from mdm2. These CTL recognized target cells expressing mdm2 endogenously, while CTL generated against the remaining peptides were of lower avidity and did not recognize cells expressing relevant proteins endogenously. Generation of high avidity anti-mdm2 CTL required several cycles of peptide stimulation, suggesting that the CTL precursor frequency was low. The data show the normal T cell repertoire contains small numbers of potentially autoreactive CTL. Expansion of these CTL may lead to beneficial autoimmunity against tumors, but, equally, it may be the basis of detrimental autoimmune diseases.

Animals↗
PubMed1996

Major histocompatibility complex and T cell receptor interaction of the P91A tum- peptide.

The P91A antigen was identified following mutation of P1 mastocytoma cells. The peptide epitope is encoded by a mutant form of the S3 subunit of the PA700 proteasome regulatory complex. P91A stimulates a strong CD8+ T cell response when expressed on tumor cells or normal tissue and P91A-specific T cells express a restricted range of T cell receptors. Although it is a strong Ld-binding peptide, P91A does not conform to the established motif for this major histocompatibility complex (MHC) molecule and this has hampered elucidation of the precise epitope. Ld predominantly associates with nonamer peptides; however, using a variety of complementary approaches, the P91A epitope is identified as the octamer QNHRALDL. In the absence of the Ld motif residue proline at position 2, residues 5-7 are primarily involved in MHC interaction. P91A is thus atypical in its interaction with Ld. Residues 1, 3, and 4 are found to influence T cell recognition of P91A. Definition of the P91A peptide will allow studies on P91A processing and interactions of the P91A peptide/MHC complex with T cell receptors of differing avidity to establish the basis for restricted T cell receptor usage. The basis for the failure of the P91A tum+ peptide (QNRRALDL) to bind to Ld is addressed by molecular modeling.

Amino Acids↗
PubMed1995

Both immunization with protein and recombinant vaccinia virus can stimulate CTL specific for the E7 protein of human papilloma virus 16 in H-2d mice.

The transforming protein E7 of human papilloma virus type 16 can stimulate cytotoxic T lymphocytes (CTL) which can protect experimental animals against growth of E7 expressing tumour cells. In this study we compared CTL responses in mice immunized with either E7 protein in MF59 adjuvant or with recombinant vaccinia virus expressing E7 (Vac-E7). We have chosen H-2d mice because no E7-specific CTL responses have been described in this MHC haplotype. Immunization of these mice with Vac-E7 generated CTL which lysed target cells infected with Vac-E7 or transfected with the E7 gene. CTL from mice immunized with E7 protein in MF59 adjuvant showed specificity for the same target cells. Antibody blocking experiments revealed that both immunization with Vac-E7 and E7 protein stimulated CD8+ effector CTL. The find specificity of CTL induced by the two immunization protocols was similar. A major CTL epitope was mapped to the carboxyl terminal amino acids 48-98 of the E7 protein. Peptide isolation from E7 expressing cells followed by HPLC separation indicated that CTL induced by immunization with protein and Vac-E7 recognized the same HPLC purified peptide fractions. Together, the study suggests that vaccines based on protein can activate CTL with similar fine specificity to CTL induced by vaccines based on recombinant vaccinia virus.

Adjuvants, Immunologic↗
PubMed1994

Strategies for studying mouse and human immune responses to human papillomavirus type 16.

Cytotoxic T lymphocytes (CTL) are an important protective mechanism in viral infection and can be effective against tumours. We have investigated the tumour-associated E6 and E7 genes of human papillomavirus type 16 as CTL targets. In H-2b mice we have defined epitopes in E6 and E7 which can readily generate CTL in vivo and we have shown that HLA-A2.1 transgenic mice can generate an HLA-A2.1-restricted response. We have been unable to reveal a primed CTL response in humans. These paradoxical findings imply that human papillomavirus may fail to stimulate a systemic CTL response and/or employ strategies for evading or down-regulating such a response.

Amino Acid Sequence↗
PubMed1994

Unconventional cytotoxic T lymphocyte recognition of synthetic peptides corresponding to residues 1-23 of Ras protein.

A peptide corresponding to amino acids 1 through 23 of Ras protein containing a mutation at position 12 was used to induce cytotoxic T lymphocytes (CTL) in mice. Although the CTL were CD8+ and expressed alpha, beta T cell antigen receptors (TCR), their major histocompatibility complex (MHC)-restriction was unconventional. They recognized peptide-treated murine cells of different H-2 haplotypes, but not MHC class I-negative cells. Human HLA class I molecules did not present Ras peptides and hybrid human/mouse MHC molecules revealed that all three extracellular domains alpha 1, alpha 2 and alpha 3 were required for recognition by peptide-specific CTL. Shortening the 23-mer peptide by 5 residues at either the amino or carboxy terminus resulted in loss of CTL recognition. This demonstrates an unusual form of antigen recognition by mouse CTL in which peptide presentation requires murine H-2 class I molecules but is not class I allele restricted, and the peptides recognized are much larger than peptides in conventional class I-restricted responses.

Amino Acid Sequence↗
PubMed1994

Limitations of predictive motifs revealed by cytotoxic T lymphocyte epitope mapping of the human papilloma virus E7 protein.

Human papilloma virus (HPV) type 16 is found in the majority of cervical cancer patients and the transforming protein E7 is consistently expressed in cancer cells, making it a potential target for immune attack. In this study we have investigated whether E7 gains access to the MHC class I processing pathway and provides cytotoxic T lymphocyte (CTL) stimulating peptide epitopes. CTL were induced in H-2b mice by immunization with recombinant vaccinia virus expressing E7 (Vac-E7). To map CTL recognition, natural peptides were purified from cells expressing either intact or truncated E7 protein. Following peptide separation by HPLC one major CTL epitope was detected and truncated constructs localized this epitope to the C-terminal region. Mapping with synthetic peptides indicated that residues 49-57 (RAHYNIVTF) were recognised by anti-E7 CTL. Synthetic 49-57 peptide was used to induce CTL, which recognized the same HPLC purified natural peptide fractions as anti-E7 CTL. Binding motifs for H-2b class I molecules did not predict residues 49-57 to be a CTL epitope, but instead the sequence 21-28 (DLYCYEQL) which contains a Kb anchor motif. Synthetic 21-28 peptide was found to bind to Kb class I molecules and readily induced CTL, indicating that the T cell repertoire of H-2b mice can recognize this epitope. However, these CTL did not recognize peptides isolated from E7 expressing cells, showing that natural processing did not produce detectable levels of the 21-28 epitope. Together, the data demonstrate that an unexpected E7 peptide can function as a major CTL epitope.

Amino Acid Sequence↗
PubMed1994

T cell epitopes in human papilloma virus proteins.

Infection by HPV is associated with several human diseases such as warts of the skin, condylomata of the genital track and carcinoma of the cervix. Although there is strong evidence for immune control of HPV types causing warts and condylomata, it is currently unclear whether patients infected with transforming HPV types can mount efficient T cell responses. Despite the apparent low immunogenicity of transforming HPV types, several Th and CTL epitopes have been identified in proteins derived from HPV16. This transforming virus is most frequently present in women with CIN and cervical carcinoma and knowledge of T cell recognisable proteins may eventually lead to the design of immune-stimulating anti-HPV16 vaccines.

Amino Acid Sequence↗
PubMed1993

Identification of two cytotoxic T lymphocyte-recognized epitopes in the Ras protein.

We have investigated the possibility of inducing cytotoxic T lymphocytes (CTL) to Ras containing a mutation at position 61 or to normal Ras, using recombinant vaccinia viruses expressing these proteins. CTL from C57Bl/10 mice immunized with vaccinia expressing mutant Ras showed specificity for the mutant Ras protein and recognition of normal Ras was inefficient. The opposite specificity was observed after immunization with vaccinia expressing normal Ras, since CTL isolated from these mice recognized normal Ras well and mutant Ras inefficiently. Levels of endogenous Ras expression were insufficient for lysis by these CTL. One CTL epitope mapped to amino acids 60-67 and residue 61 was critical for T cell recognition. CTL generated against mutant Ras protein recognized peptide 60-67 containing mutant residue 61, while anti-normal Ras CTL recognized the wild-type 60-67 sequence. A second epitope mapped to residues 152-159 of Ras and was recognized equally well by CTL raised to normal or mutant Ras. The murine data raise the possibility of exploiting Ras-specific CTL for targeted immunotherapy of certain human cancers.

Amino Acid Sequence↗
PubMed1993

Few peptides dominate cytotoxic T lymphocyte responses to single and multiple minor histocompatibility antigens.

Minor histocompatibility (H) antigens are T cell recognized self proteins which can cause graft versus host disease or organ transplant rejection. We have analysed the number of peptide epitopes involved in cytotoxic T lymphocyte (CTL) responses to single or multiple minor H antigens. Bulk CTL responses were generated in H-2b mice differing in one (H-1), two (H-1 and H-25), or multiple (> 29) minor H loci, and HPLC separation was used to analyse the complexity of CTL recognized peptides. Anti-H-1 CTL recognize one out of 50 HPLC peptide fractions and recognition is H-2Kb restricted. The same peptide fraction is also recognized by anti-H-1/H-25 CTL and no additional epitopes are detected, indicating that the H-25 locus does not stimulate CTL when combined with H-1. CTL generated to multiple minor H loci (including H-1 and H-25) recognize two HPLC peptide fractions which are presented by H-2Db and H-2Kb class I molecules, respectively. The H-2Kb presented fraction is the same as that recognized by anti-H-1 and anti-H-1/H-25 CTL, and it is shown to contain a H-1-derived peptide. Subfractionation of the CTL recognized HPLC fractions is consistent with the presence of only one peptide epitope. Thus, in the responses analysed here one minor H locus encodes probably only one CTL epitope. The study provides a molecular explanation for immunodominance among minor H antigens, suggesting that dominant loci encode single peptide epitopes which are presented efficiently by MHC class I molecules enabling them to readily stimulate CTL responses.

Animals↗
PubMed1993

CD4-positive and B lymphocytes in transplantation immunity. I. Promotion of tumor allograft rejection through elimination of CD4-positive lymphocytes.

The elimination of CD4+ cells by anti-CD4 antibody caused regression of a malignant solid tumor allograft that does not lose a cytotoxic T lymphocyte-defined target antigen during tumor progression and requires specific CD8+ CTL for tumor rejection. Treatment with anti-CD4 antibody was effective when started 1-2 weeks after tumor challenge and was at least as effective as treating with anti-CD3 antibody or specific immunization with the antigen expressed on malignant or nonmalignant cells. None of these treatments caused rejection of tumors that were larger than 1 cm3 or had been growing for 3 weeks or longer in the host. Mice bearing large and long-established tumors treated with anti-CD4 antibody rejected a new tumor challenge but failed to reject the long-established tumor. Similarly, mice with established tumors mounted effective CTL responses to reject skin grafts but failed to reject tumors which expressed the same antigen. Treatment with anti-CD4 antibody eliminated primary T lymphocyte dependent antibody responses but failed to suppress ongoing antibody responses to continuous antigenic stimulation. Possibly, the effectiveness of early treatment and the failure of later treatment with anti-CD4 antibody results indirectly from the effect treatment has on B lymphocytes.

Animals↗
PubMed1993

T cell recognition of a point mutation in the P21 Ras protein.

Point mutations of p21 Ras proteins correlate with many human malignancies. To determine whether the mutations of Ras proteins generate immunogenic determinants which can be recognized by T cells and possibly serve as targets for immunotherapy, we studied the murine T helper responses to synthetic Ras peptides corresponding to amino acids 1-23 of normal or mutant Ras protein. Immunization of C3H/He and B10.BR mice with Ras peptides containing a valine mutation at position 12 stimulated MHC class II-restricted T helper cells which recognised specifically the Ras mutation. Surprisingly C57BL/10 mice generated T helper responses not only against mutant but also against normal Ras peptides. Importantly, natural processing of Ras protein was found to generate the epitopes recognized by the peptide-induced T cells.

Amino Acid Sequence↗
PubMed1992

Induction of cytotoxic T lymphocytes with peptides in vitro: identification of candidate T-cell epitopes in human papilloma virus.

A set of overlapping peptides corresponding to the L1, E6, and E7 proteins of human papilloma virus 16 was tested for their ability to bind to major histocompatibility complex class I molecules and to stimulate cytotoxic T-lymphocyte (CTL) responses in vitro. A class I binding assay using intact RMA-S cells showed that 20 of the 99 human papilloma virus peptides bound to H-2Kb and/or Db molecules. Fifteen of the 20 class I-binding peptides stimulated primary CTL responses, whereas peptides that were negative in the binding assay failed to do so. Peptide-induced CTLs recognized the immunizing peptide very efficiently, requiring no more than 1-10 nM peptide for target cell lysis. However, two observations were made that have important implications for the design of peptide-based vaccines for inducing CTLs. (i) Not all major histocompatibility complex-binding peptides that contained known motifs characteristic of naturally processed peptides induced CTLs. (ii) The efficiency of CTL lysis was strongly decreased when the size of the target peptide differed by only one amino acid residue from that of the immunizing peptide. We conclude that peptides chosen for vaccination must correspond in length to naturally processed peptides.

Animals↗
PubMed1992

A cross-species functional interaction between the murine major histocompatibility complex class I alpha 3 domain and human CD8 revealed by peptide-specific cytotoxic T lymphocytes.

The monomorphic cell surface glycoprotein CD8 acts as co-receptor in the recognition of peptide-major histocompatibility complex (MHC) class I complexes by cytotoxic lymphocytes (CTL) by binding to the monomorphic alpha 3 domain of the class I molecule. Positions 227 and 245 in the class I alpha 3 domain appear to be especially important for this interaction. Recent reports suggest there is no interspecies recognition between CD8 and MHC class I. In this study, hybrid genes from human class I HLA-A0201 and murine class I H-2Kb were transfected into human and mouse cells and tested in Cr-release assays using HLA-A0201-restricted influenza A matrix peptide-specific CTL as effectors. Transfected cells expressing chimeric genes comprising the alpha 1 and alpha 2 domains from HLA-A0201 together with the H-2Kb alpha 3 domain were lysed as effectively as wild-type HLA-A0201 and in both cases, killing was blocked by anti-CD8 antibody equally well. These results indicate that human CD8 can interact with the alpha 3 domain of murine class I to the same level as human class I.

Animals↗
PubMed1991

Different types of allospecific CTL clones identified by their ability to recognize peptide loading-defective target cells.

Allospecific immune responses against the MHC of another individual are remarkably strong, due t a high number of responding T cell clones. Although it has been demonstrated that some allospecific cytotoxic T lymphocytes (CTL) recognize peptides presented by allogeneic MHC class I molecules, it has remained unclear whether MHC molecules can be recognized directly. We used the H-2b-derived murine lymphoma mutant RMA-S, which has a defect affecting peptide loading of class I molecules, to test whether recognition by allospecific CTL always requires the presence of peptides. Three types of anti-H-2Kb CTL clones can be distinguished by their ability to lyse RMA-S target cells. Type A CTL clones efficiently lyse these target cells, the lysis by type B CTL clones is inefficient, and type C clones fail to lyse RMA-S. Up-regulation of the levels of H-2Kb density improved lysis by type B clones, but did not lead to lysis by type C clones. Some type A and B CTL clones apparently can recognize class I molecules devoid of peptides, while others are likely to recognize peptides which are not affected by the presentation defect of RMA-S. We suggest that type C clones are specific for peptides which are not presented by the mutant cells. The results show that the majority of alloreactive CTL recognize peptide/MHC complexes, while some CTL behave as if they can recognize class I molecules in the absence of MHC-bound peptides.

Animals↗
PubMed1991

The CD45RA molecule is expressed in naive murine CTL precursors but absent in memory and effector CTL.

We have studied the expression of the CD45RA molecule in murine cytotoxic T lymphocytes (CTL) specific for the allogeneic H-2Kb molecule at different stages of differentiation. The CD45RA phenotype of naive H-2Kb-specific CTL precursors has been determined using primary in vitro CTL responses. For the analysis of memory CTL we have immunized mice in vivo followed by restimulation in vitro. We have also determined the CD45RA expression at the CTL effector stage. Our results show that among naive CD8+ T cells both the CD45RA+ and the CD45RA- subpopulations can mount Kb-specific CTL responses. In contrast, memory CTL responses are mediated only by the CD8+ CD45RA+ T cell subpopulation. Similarly, effector CTL are CD8+ CD45RA- while the CD8+ CD45RA+ subpopulation does not exhibit specific cytolytic activity. The data indicate that CD45RA expression changes during CTL differentiation and that memory as well as effector CTL lack this marker.

Animals↗