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C J Melief

Publications and source records attributed to C J Melief.

At least 19 recordsLinked to original sources
PubMed1996

Occasional memory cytotoxic T-cell responses of patients with human papillomavirus type 16-positive cervical lesions against a human leukocyte antigen-A *0201-restricted E7-encoded epitope.

Most cervical carcinoma (Cxca) cells constitutively express human papillomavirus type 16 (HPV16) E6 and E7 oncoproteins. These proteins are, therefore, attractive targets for T cell-based immunotherapy. Previously, we identified HVP16 E7-encoded CTL epitopes. In patients with cervical intraepithelial neoplasia or Cxca, little is known concerning T-cell activity against viruses in general and against HPV16 in particular. Here, we have screened the blood of 10 healthy donor controls and of 22 patients with HPV16+ cervical lesions for the presence of CTLs directed against HPV16 E7- and control influenza virus matrix-derived epitopes presented by HLA-A *0201. We detected influenza virus-specific CTLs in all donors and in the majority of patients, indicating that most patients have functioning T-cell responses despite their lesions or therapeutic interventions. Moreover, we show that patients with HPV16+ lesions occasionally have memory CTLs against a HPV16 E7-encoded epitope (sequence YMLD-LQPETT), providing evidence for natural CTL immunity against HPV16 in patients with cervical lesions. Combined, these findings raise possibilities for vaccination with HPV16 E7-encoded peptides to induce or augment CTL responses for treatment or prevention of Cxca.

Amino Acid Sequence↗
PubMed1995

Antigen capture and major histocompatibility class II compartments of freshly isolated and cultured human blood dendritic cells.

Dendritic cells (DC) represent potent antigen-presenting cells for the induction of T cell-dependent immune responses. Previous work on antigen uptake and presentation by human DC is based largely on studies of blood DC that have been cultured for various periods of time before analysis. These cultured cells may therefore have undergone a maturation process from precursors that have different capacities for antigen capture and presentation. We have now used immunoelectron microscopy and antigen presentation assays to compare freshly isolated DC (f-DC) and cultured DC (c-DC). f-DC display a round appearance, whereas c-DC display characteristic long processes. c-DC express much more cell surface major histocompatibility complex (MHC) class II than f-DC. The uptake of colloidal gold-labeled bovine serum albumin (BSA), however, is greater in f-DC, as is the presentation of 65-kD heat shock protein to T cell clones. The most striking discovery is that the majority of MHC class II molecules in both f-DC and c-DC occur in intracellular vacuoles with a complex shape (multivesicular and multilaminar). These MHC class II enriched compartments (MIIC) represent the site to which BSA is transported within 30 min. Although MIIC appear as more dense structures with less MHC class II molecules in f-DC than c-DC, the marker characteristics are very similar. The MIIC in both types of DC are acidic, contain invariant chain, and express the recently described HLA-DM molecule that can contribute to antigen presentation. CD19+ peripheral blood B cells have fewer MIIC and surface MHC class II expression than DCs, while monocytes had low levels of MIIC and surface MHC class II. These results demonstrate in dendritic cells the elaborate development of MIIC expressing several of the components that are required for efficient antigen presentation.

Animals↗
PubMed1995

Eradication of large human B cell tumors in nude mice with unconjugated CD20 monoclonal antibodies and interleukin 2.

Since antibody-dependent cellular cytotoxicity is considered an important mechanism by which mAbs may exert their antitumor effects, it seems likely that these antitumor effects can be enhanced by the activation of the appropriate effector cell populations. We have used nude mice xenografted with human Daudi tumor cells as a model to compare the antilymphoma effects of unconjugated CD19 (CLB-CD19) and CD20 (BCA-B20) mAbs (IgG2a subclass) alone or in combination with recombinant human interleukin 2 (rhIL-2) or recombinant mouse granulocyte-macrophage-colony-stimulating factor (rmGM-CSF). Treatment of established tumors with BCA-B20 or rhIL-2 or rmGM-CSF as a single agent, all resulted in highly significant decreases of tumor growth rates, but did not increase the number of complete regressions. The combination of CLB-CD19 or BCA-B20 mAbs with rhIL-2 or rmGM-CSF resulted in larger decreases of growth rates than either of the agents alone. Complete eradication of large Daudi tumors could be achieved when treatment with BCA-B20 mAbs was combined with rhIL-2, but not with the combination of CLB-CD19 mAbs and rhIL-2 nor with the combination of BCA-B20 mAbs and rmGM-CSF. Cured animals kept for 2-3 months after complete regression of the tumors were still tumor free. Regression of tumors was correlated with the infiltration of lymphocytes as well as macrophages into the tumor. This is the first report to show that unconjugated CD20 mAbs are to be preferred over unconjugated CD19 mAbs, and interleukin 2 over GM-CSF in the combinational treatment of large B cell tumors.

Animals↗
PubMed1995

Human CTL epitopes encoded by human papillomavirus type 16 E6 and E7 identified through in vivo and in vitro immunogenicity studies of HLA-A*0201-binding peptides.

Human papillomavirus type 16 (HPV16) is strongly associated with cervical carcinogenesis. The HPV16 E6 and E7 oncoproteins are constitutively expressed in the majority of cervical tumor cells and are, therefore, attractive targets for CTL-mediated immunotherapy. In mice, the outgrowth of a lethal dose of HPV16-induced tumor cells has been prevented by vaccination with a CTL epitope encoded by HPV16 E7, indicating the feasibility of peptide immunization to obtain antitumor CTL responses. In the present study, the immunogenicity of 9 HLA-A*0201-binding peptides encoded by HPV16 E6 and E7 was analyzed in vivo in HLA-A*0201Kb transgenic mice and in vitro in CTL cultures induced from PBMC of HLA-A*0201+ healthy donors. Four peptides with a good binding affinity were immunogenic in HLA-A*0201Kb transgenic mice, and three of them were also highly immunogenic in CTL induction experiments with PBMC of HLA-A*0201+ healthy donors. Human CTL clones specific for these three peptides were capable of lysing the HPV16 E7-containing HLA-A*0201+ cervical carcinoma cell line CaSki. These E7-derived peptides (11-20, YMLDLQPETT; 82-90, LLMGTLGIV; 86-93, TLGIVCPI), therefore, are likely to represent naturally processed human CTL epitopes of HPV16. Additionally, these three HPV16-encoded peptides have the highest affinity of binding to the HLA-A*0201 molecule. In this study, peptides with a lower binding affinity were less immunogenic. Therefore, our data illustrate that the HLA-binding affinity of a peptide has a major impact on its immunogenicity. In conclusion, we have identified immunogenic peptides encoded by HPV16 E6 and E7 that could be used in vaccines for the prevention and treatment of cervical carcinoma.

Amino Acid Sequence↗
PubMed1995

MHC class II compartments and the kinetics of antigen presentation in activated mouse spleen dendritic cells.

MHC class II (MHC-II) molecules bind fragments of exogenous Ags in an intracellular endocytotic compartment. In view of divergent data on the MHC-II distribution in different cell lines, it was of interest to localize MHC-II molecules in a natural and the most potent APC type, the dendritic cell (DC). By using immunogold labeling of ultrathin cryosections of cultured mouse spleen DC, we found that MHC-II molecules were present abundantly at the plasma membrane and in intracellular compartments containing internal membrane vesicles and/or membrane sheets. The majority of these compartments was situated late in the endocytotic route, as demonstrated by the late appearance (after a lag of 30 min) of internalized exogenous tracer. These compartments contained the lysosomal enzymes cathepsin D and beta-hexosaminidase, but lacked the late endosomal marker cation-dependent mannose-6-phosphate receptor. We conclude that most of the intracellular MHC-II molecules in cultured spleen DC reside in a compartment with (pre)lysosomal characteristics, resembling the so-called MHC-II-enriched compartments (MIIC), originally described in B cells. We also investigated whether the presence of MHC-II molecules in endocytotic compartments was related to the kinetics of Ag processing and presentation by these cells. Pulse-chase endocytosis experiments with hen egg lysozyme (HEL) as a model Ag showed that activated spleen DC were able to efficiently process and present this Ag to an HEL-specific T hybridoma cell line. However, presentation started only after a lag of 2 h and was maximal after 6 h. The difference in time between the arrival of Ag in proteolytic endocytotic compartments, in particular MIIC, and effective Ag presentation is discussed in the context of DC maturation.

Animals↗
PubMed1995

Induction and characterization of cytotoxic T-lymphocytes recognizing a mutated p21ras peptide presented by HLA-A*0201.

The ras oncogene is frequently found to be activated in human cancer through point mutations at codons 12, 13 or 61. We explored whether these altered p21ras protein sequences contain peptide sequences that can activate naive CD8+ cytotoxic T lymphocytes (CTL). Several wild-type and mutated p21ras peptides were identified that carry a binding motif for human leukocyte antigen (HLA)-A*0201. Two peptides were found to bind strongly to this allele. CD8+ CTL bulk cultures specifically reacting with one of these peptides could be induced, using processing-defective T2 cells loaded with peptide CLLDILDTAGL as stimulators. The peptide is derived from p21ras, position 51-61, and carries a 61 Gln-->Leu mutation. In contrast, a 9-mer peptide CLLDILDTA corresponding to amino acid sequence 51-59 of wild-type p21ras did not yield reactive CTL cultures. T-cell clones with low affinity for the 11-mer peptide were isolated from CLLDILDTAGL-reactive bulk cultures. These T cells did not lyse melanoma cells transfected with 61-Leu N-ras, although lysis was found when these transfectants were pulsed with the 11-mer peptide. Possibly, T cells of higher affinity may be required to demonstrate processed peptide on the cell surface. The combined experiments suggest that a peptide derived from mutated p21ras can be recognized by HLA class I-restricted CTL, whereas an analogous wild-type p21ras peptide may not be immunogenic.

Alleles↗
PubMed1995

CTL specific for the tyrosinase autoantigen can be induced from healthy donor blood to lyse melanoma cells.

CTL that lyse melanoma cells were previously isolated from several melanoma patients. Such CTL recognize autologous proteins, indicating the occurrence of autoreactive T cells in melanoma patients. We have now raised CTL, using responding T lymphocytes from healthy donor blood, that lysed not only cells incubated with an HLA-A*0201-binding tyrosinase peptide but also melanoma cells endogenously processing and presenting the epitope. Our results suggest that autoreactive CTL precursors are present in healthy donor blood and can be activated in vitro with synthetic peptides presented on appropriate APCs. Therefore, tissue-specific, autoantigen-derived peptides might be useful in immunotherapy of both poorly and nonimmunogenic tumors.

Amino Acid Sequence↗
PubMed1995

An adenovirus type 5 early region 1B-encoded CTL epitope-mediating tumor eradication by CTL clones is down-modulated by an activated ras oncogene.

Mouse embryo cells (C57BL/6, H-2b) transformed by the E1A and E1B genes of adenovirus type 5 (Ad5E1 MEC) are highly immunogenic. Previously, CTL were cloned from mice immunized with Ad5E1 MEC. These CTL clones were capable of tumor eradication in nude mice, and were directed against the Ad5E1A-encoded decapeptide SGPSNTPPEI, presented by the H-2Db MHC molecule. We have now generated Ad5E1 MEC containing a mutated Ad5E1A-encoded epitope. The mutant Ad5E1 MEC induce a strong CTL response when injected into immunocompetent mice. CTL clones generated against mutant Ad5E1-transformed tumor cells recognize an Ad5E1B-encoded epitope (VNIRNCCYI) in the context of H-2Db. Because this epitope is also present on wild-type Ad5E1 MEC, it is concluded that Ad5E1-transformed tumor cells express at least two CTL epitopes. Interestingly, the lysis of Ad5E1 MEC by the Ad5E1B-specific, but not by the Ad5E1A-specific, CTL clones was strongly diminished by the action of the activated ras oncogene. CTL directed against the Ad5E1B-encoded epitope were, like Ad5E1A-specific CTL, able to eradicate large established Ad5E1-induced tumors in B6 nude mice, demonstrating that CTL activity directed against different CTL epitopes expressed by the same tumor can be exploited for immunotherapy of cancer.

Adenovirus E1 Proteins↗
PubMed1995

Enhanced antitumor effects of CD20 over CD19 monoclonal antibodies in a nude mouse xenograft model.

We used a nude mouse xenograft tumor model to compare the efficacy of unconjugated CD19 and CD20 mAbs (IgG2a subclass) in mediating antilymphoma effects. Treatment with the CD20 mAbs NKI-B20 and BCA-B20 resulted in a drastic decrease in tumor take rate (P < 0.0001) in comparison to controls, whereas the CD19 mAb CLB-CD19 was ineffective. Tumor growth rates were reduced by both CD19 and CD20 (P < 0.0001). The decrease in growth rate induced by NKI-B20 or BCA-B20 was larger than that induced by CLB-CD19 (P = 0.0022). In vitro experiments showed that NKI-B20 or BCA-B20 are more powerful than CLB-CD19 in mediating lysis by interleukin 2-activated natural killer cells. No difference was observed between different isotypes (IgG1, IgG2a, IgG2b) of the switch variants of NKI-B20 or CLB-CD19. A positive correlation between antigen density and the sensitivity to antibody-dependent cellular cytotoxicity was demonstrated with human lymphoblastoid B cells, JY, transfected with cDNA encoding the human CD19 antigen that expressed high levels of this antigen. These cells are more efficiently killed by natural killer cells when coated with CLB-CD19 mAbs than JY wildtype cells that express 1 log lower levels of the CD19 antigen. Antibody-dependent cellular cytotoxicity experiments with thioglycolate-activated macrophages show a more complex relationship between antigen density, isotype of the mAb, and cytotoxicity. BCA-B20 (IgG2a) and CLB-CD19 (IgG2a) and all isotypes of NKI-B20 mediated strong cytotoxicity, whereas CLB-CD19 isotypes IgG1 and IgG2b were associated with limited cytotoxicity. Proliferation of Daudi cells was inhibited with high concentrations of all isotypes of CLB-CD19, but not with any of the CD20 mAbs. To our knowledge this is the first report showing that the antitumor effects in vivo of unconjugated CD20 mAbs are far superior to those of CD19 mAbs.

Animals↗
PubMed1995

Major differences in transporter associated with antigen presentation (TAP)-dependent translocation of MHC class I-presentable peptides and the effect of flanking sequences.

The MHC-encoded transporter associated with Ag presentation (TAP) translocates peptides from the cytosol to the ER lumen, where association with MHC class I molecules occurs. The MHC class I/peptide complex is subsequently transported to the cell surface for presentation to CD8+T cells. We studied TAP-dependent translocation of defined MHC class I presentable murine peptides by competition for translocation of a radiolabeled model peptide, to address whether efficient peptide presentation by MHC class I molecules is preceded by equal efficient peptide translocation by TAP. Surprisingly, we observed that four immunodominant viral peptides of 16 peptides tested were very inefficiently transported by TAP. Inefficient translocation could be overcome by substitution of a proline residue present at position 3 in the peptides. Furthermore, addition of natural flanking amino acids directly surrounding a poorly transported peptide could considerably improve translocation by TAP. Our data suggest that some peptides are efficiently transported by TAP in their optimal size for MHC class I binding, whereas other peptides are transported as larger peptide fragments that need further trimming in the ER for MHC class I binding.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Cytotoxic T lymphocytes raised against a subdominant epitope offered as a synthetic peptide eradicate human papillomavirus type 16-induced tumors.

Previously, we have shown that immunization with human papillomavirus (HPV) type 16-derived cytotoxic T lymphocyte (CTL) epitope E7 49-57 (RAHYNIVTF) renders C57BL/6 mice insensitive to tumors formed by HPV16-transformed cells. In this study, we provide evidence that E7 49-57 is expressed as a subdominant CTL epitope on HPV16-transformed C57BL/6 cells. Using acid peptide elution, it is shown that HPV16-transformed cells express another CTL epitope, besides E7 49-57, which appears to be dominant. We demonstrate that a CTL line raised against the subdominant CTL epitope, offered as synthetic peptide E7 49-57, eradicates established HPV16-induced tumors in mice. Our data show that synthetic peptide-induced CTL can be applied successfully in vivo against (virus-induced) tumor, and emphasize that subdominant CTL epitopes are useful targets for immunotherapy. Furthermore, it is illustrated for the first time that HPV16-specific CTL interfere directly with HPV16-induced tumors.

Animals↗
PubMed1995

Treatment of low-grade non-Hodgkin's lymphoma with continuous infusion of low-dose recombinant interleukin-2 in combination with the B-cell-specific monoclonal antibody CLB-CD19.

Seven patients with low-grade non-Hodgkin's lymphoma were treated with a combination of a murine monoclonal antibody directed against the B-cell-specific antigen CD19 (CLB-CD19), given twice weekly, and continuous infusion of low-dose recombinant interleukin-2 (rIL-2). We demonstrated stable serum CLB-CD19 levels throughout the 12 weeks of treatment, and homing of the antibody into the tumour sites. A variable degree of antigenic modulation was noted. Prolonged treatment resulted in a sustained increase in the number of natural killer cells in the circulation with enhanced cytotoxic capacity, including antibody-dependent cellular cytotoxicity. During the first weeks of treatment, T cell activation occurred in the majority of patients. Toxicity was related to the rIL-2 treatment and consisted of transient constitutional symptoms and a flu-like syndrome without organ dysfunction. A partial remission occurred in one patient, and in another patient who was primarily leukaemic a greater than 50% reduction of circulating B cells was noted. An antitumour effect occurred early during treatment and could not be related to rIL-2-induced modulation of natural killer cell or T lymphocyte activation.

Adult↗
PubMed1995

Detailed motifs for peptide binding to HLA-A*0201 derived from large random sets of peptides using a cellular binding assay.

Extensive sets of in total about 2000 synthetic peptides were investigated for their binding affinities to HLA-A*0201. Comparisons of the amino acid compositions of binding to nonbinding sets of peptides provided new information concerning the rules for 9-, 10-, and 11-mer peptide binding at the amino acid level. Preferred primary anchors were shown to depend on peptide length, longer peptides being more demanding in this respect. A clear preference exists for certain amino acids at several nonanchor positions. In addition, the presence of particular amino acids at those positions almost completely precludes peptide binding. We found no evidence for preferred anchor pairs. From these results new and detailed HLA-A*0201 peptide-binding motifs for 9-, 10-, and 11-mer peptide binding were deduced. The motifs are in accordance with earlier reports but include new findings, including C as a C-terminal anchor, the importance of D at positions 4 for binding, and the deleterious effect of R at position 5 (in 9-mers). The motifs are presented in such a way that they can be used to predict peptide binding to HLA-A*0201 by computer analysis (see accompanying paper [56]).

Alleles↗
PubMed1995

A computer program for predicting possible cytotoxic T lymphocyte epitopes based on HLA class I peptide-binding motifs.

Vaccination with peptides recognized by antigen-specific CTLs can prevent lethal virus infections and tumor growth. In order to avoid the synthesis and testing of the numerous overlapping peptide of long AA sequences of proteins of interest, we developed a computer program which utilizes the rules, "motifs" which govern how peptides bind to HLA class I molecules, to derive a predicted binding score for each overlapping peptide. Correlations between the predicted and actual binding results to HLA-A*0201 for 100 peptides selected from six early and two late protein sequences of human papillomavirus type 1a revealed an acceptable level (61%) of concordance. The program is very flexible with regard to the input of protein sequences and motif definitions and is able to handle various motif and peptide lengths.

Amino Acid Sequence↗
PubMed1995

Antibodies against p53 are associated with poor prognosis of colorectal cancer.

Mutation of the p53 gene is a common event in colorectal cancer. This alteration can result in cellular accumulation of p53 and may also induce p53 antibodies. Accumulation of p53 in tumour cells has been associated with poor prognosis of colorectal cancer. We tested preoperative sera from 255 patients with colorectal cancer by enzyme-linked immunosorbent assay (ELISA). A total of 70.2% had reactivity that was higher than the 'low' control serum. Employing a cut-off level of 10% of the 'high' control sample, 25.5% of the patients were positive for p53 antibodies. The presence of p53 antibodies correlated with the following prognostic factors: histological differentiation grade, shape of the tumour, and tumour invasion into blood vessels. Patients with p53 antibodies were shown to have decreased survival and decreased disease-free survival. Specifically for patients with cancer stage A and B1 the presence of p53 antibodies selected a subgroup with poor prognosis.

Antibodies, Neoplasm↗
PubMed1995

Bone marrow-derived dendritic cells pulsed with synthetic tumour peptides elicit protective and therapeutic antitumour immunity.

Dendritic cells, the most potent 'professional' antigen-presenting cells, hold promise for improving the immunotherapy of cancer. In three different well-characterized tumour models, naive mice injected with bone marrow-derived dendritic cells prepulsed with tumour-associated peptides previously characterized as being recognized by class I major histocompatibility complex-restricted cytotoxic T lymphocytes, developed a specific T-lymphocyte response and were protected against a subsequent lethal tumour challenge. Moreover, in the C3 sarcoma and the 3LL lung carcinoma murine models, treatment of animals bearing established macroscopic tumours (up to 1 cm2 in size) with tumour peptide-pulsed dendritic cells resulted in sustained tumour regression and tumour-free status in more than 80% of cases. These results support the clinical use of tumour peptide-pulsed dendritic cells as components in developing effective cancer vaccines and therapies.

Animals↗