Biomedical subjects

B Fisk

Publications and source records attributed to B Fisk.

15 recordsLinked to original sources

PubMed1999

HER-2/neu peptide specificity in the recognition of HLA-A2 by natural killer cells.

Although natural killer (NK) cells have been described as non-MHC-restricted, new evidence suggests that NK activity can be either up- or down-regulated after interaction with the peptide-MHC-class-I complex expressed on target cells. However, the epitope(s) recognized by NK cells have remained ill-defined. We investigated NK cell recognition of synthetic peptides representing a portion of a self-protein encoded by the HER-2/neu (HER-2) proto-oncogene and presented by HLA-A2. HER-2 nonapeptides C85, E89, and E75 were found partially to protect T2 targets from lysis by freshly isolated and interleukin-2(IL-2)-activated NK cells (either HLA-A2(+) or A2(-)). This inhibition was not solely due to changes in the level of HLA-A2 expression or conformation of serological HLA-A2 epitopes. Using single-amino-acid variants at position 1 (P1) of two HER-2 peptides, we observed that protection of targets was dependent on the sequence and the side-chain. These results suggest similarities in the mechanism of target recognition by NK and T cells. This information may be important for understanding the mechanisms of tumor escape from immunosurveillance and could help explain the aggressiveness of HER-2-overexpressing tumor cells.

Cells, Cultured↗

PubMed1998

Increased sensitivity of adriamycin-selected tumor lines to CTL-mediated lysis results in enhanced drug sensitivity.

The emergence of drug resistance to chemotherapeutic agents is a major cause of treatment failure in cancer therapy. Therefore, much effort has been aimed at circumventing or reversing this undesired effect. Recently, we found that tumor cell lines selected for their multidrug-resistant phenotype can also exhibit increased levels of TAP mRNA and MHC class I proteins. This raised the question of whether drug-resistant tumors are more readily recognized by MHC-restricted CTLs. In this report, we show that five of five MHC class I+ tumor cell lines grown in medium containing Adriamycin developed into variants that expressed higher levels of MHC class I than did their corresponding parental cell lines. This was not observed with a MHC class I- cell line. No similar association was noted for changes in the expression of either HER-2 or intercellular adhesion molecule 1 protein. We also found that MHC class I+ drug-selected variants were more readily lysed by MHC-restricted, tumor-associated CTLs than were the drug-sensitive parental cell lines. When the drug-selected variants were cocultured with the same CTLs to eliminate tumor cells expressing higher levels of MHC-I (MHC-Ihi), the CTL-resistant tumor cells exhibited a drug sensitivity profile similar to that of the parental cell lines that were not exposed to Adriamycin. These findings suggest that certain chemotherapeutic drugs may increase the immunogenicity of some tumors, and that CTL immunotherapy may help reverse drug resistance.

Antibiotics, Antineoplastic↗

PubMed1998

Ovarian cancer-associated lymphocyte recognition of folate binding protein peptides.

BACKGROUND: Tumor-associated lymphocytes (TAL) isolated from ovarian cancer patients contain cytotoxic T lymphocytes (CTL) capable of recognizing specific HLA/peptide complexes on tumor cells leading to tumor cell lysis. Currently, HER2/neu, overexpressed in only 30% of breast and ovarian cancers, is the only known source of CTL-recognized peptides in epithelial cancers. Therefore, we have investigated peptides derived from folate binding protein (FBP), which is over-expressed in more than 90% of ovarian cancers and in the majority of other epithelial tumors. METHODS: TAL were isolated from the malignant ascites of four consecutive HLA-A2+ ovarian cancer patients and incubated in IL-2. Initial chromium-release assays were performed within 1 week. T2 cells, incubated with peptide, were used to reconstitute T cell epitopes. The FBP sequence was interrogated for HLA-A2 binding peptides, and five were synthesized (E37-41). RESULTS: Freshly cultured, unstimulated ovarian TAL recognize peptides derived from FBP. These peptides are presented in the context of HLA-A2, and are specifically recognized in a HLA class I-restricted fashion. TAL recognition of these reconstituted T cell epitopes is concentration dependent. Furthermore, the FBP peptides are shown by cold target inhibition studies to be naturally processed and presented antigens. CONCLUSIONS: FBP peptides are recognized by freshly isolated TAL from ovarian cancer patients, suggesting in vivo expression and sensitization. Because FBP is over-expressed 20-fold in most adenocarcinomas, these peptides may be used in a widely applicable peptide-based vaccine for epithelial tumors.

Cancer Vaccines↗

PubMed1997

Identification of naturally processed human ovarian peptides recognized by tumor-associated CD8+ cytotoxic T lymphocytes.

Identification of naturally processed peptides recognized by tumorspecific CTLs may lead to epitope-specific tumor vaccines. Because these epitopes may be expressed differently on epithelial tumors and may differ in their ability to induce CTL in vivo, we have isolated the HLA-A2-peptide complexes by immunoaffinity from an established ovarian tumor line transfected with and expressing HLA-A2 gene. High-performance liquid chromatography-fractionated peptides were used to reconstitute epitopes recognized on HLA-A2 by three HLA-A2+ CD8+ CTL lines. These lines recognized at least three of the same groups of fractions (designated SKOV3.A, -B, and -C) but showed differences in the pattern of recognition of other fractions. To gain insight in the epitope distribution by freshly isolated ovarian tumors, we compared the recognition of peaks SKOV3.B and -C with the corresponding peaks from an ovarian tumor (OVA-6) that expressed similar levels of HLA-A2, using one of these lines (CTL-OVA-5) as indicator. CTL-OVA-5 recognized a large number of epitopes from peaks B and C rechromatographed on more resolving high-performance liquid chromatography gradient. Although a number of peaks appeared to be coincident on both SKOV3 and OVA-6, an even higher number appeared either not to overlap or to overlap only partially. These findings, which represent the first analysis of the epitopes presented by a patient tumor, suggest that the use of tumor line-derived peptides for vaccination may require selection of the epitopes corresponding to the ones presented by freshly isolated human tumors.

Antigens, Neoplasm↗

PubMed1995

Identification of an immunodominant peptide of HER-2/neu protooncogene recognized by ovarian tumor-specific cytotoxic T lymphocyte lines.

Synthetic peptide analogues of sequences in the HER-2 protooncogene (HER-2) were selected based on the presence of HLA-A2.1 anchor motifs to identify the epitopes on HER-2 recognized by ovarian tumor-reactive CTL. 19 synthetic peptides were evaluated for recognition by four HLA-A2 ovarian-specific cytotoxic T lymphocyte (CTL) lines obtained from leukocytes associated with ovarian tumors. The nonapeptide E75 (HER-2, 369-377:KIFGSLAFL) was efficient in sensitizing T2 cells for lysis by all four CTL lines. This peptide was specifically recognized by cloned CD8+ CTL isolated from one of the ovarian-specific CTL lines. E75-pulsed T2 cells inhibited lysis by the same CTL clone of both an HLA-A2+ HER-2high ovarian tumor and a HER-2high cloned ovarian tumor line transfected with HLA-A2, suggesting that this or a structurally similar epitope may be specifically recognized by these CTL on ovarian tumors. Several other HER-2 peptides were recognized preferentially by one or two CTL lines, suggesting that both common and private HER-2 epitopes may be immunogenic in patients with ovarian tumors. Since HER-2 is a self-antigen, these peptides may be useful for understanding mechanisms of tumor recognition by T cells, immunological tolerance to tumor, and structural characterization of tumor antigens.

Amino Acid Sequence↗

PubMed1995

Changes in an HER-2 peptide upregulating HLA-A2 expression affect both conformational epitopes and CTL recognition: implications for optimization of antigen presentation and tumor-specific CTL induction.

The HER-2/neu protooncogene (HER-2) is overexpressed in a significant number of breast and ovarian tumors. Peptides of HER-2 sequence were recently found to reconstitute recognition of cytotoxic T lymphocytes (CTLs) from tumor-associated (TALs) and tumor-infiltrating (TILs) lymphocytes, indicating that they reconstitute natural epitopes recognized by CTLs on HLA-A2+ tumors. Because HER-2 is an important antigen (Ag) for tumor-specific CTL induction and the immunogenicity of peptides for CTL induction is dependent on their presentation as stable complexes with HLA-A2, we identified peptides of high and low stabilizing activity from the sequence of HER-2 and the folate-binding protein (FBP). Distinct sequence patterns in the region positions (P)3-P5 and P1 were found for peptides with high (HSA) and low (LSA) stabilizing ability. A low-HLA-A2-affinity HER-2 peptide, P1 of the CTL epitope, was found to be permissive to substitutions that enhanced HLA-A2-stabilizing ability and conserved CTL recognition. In contrast, the region P3-P5 was not permissive to sequence changes. We conclude that the selective permissivity of P1 and P9 in the tumor epitope sequence may have important implications for optimization of tumor Ag presentation, and "neoantigenicity" of self-antigens, aiming toward induction of tumor-reactive CTLs of defined affinity and specificity for target Ags.

Amino Acid Sequence↗

PubMed1994

Oligopeptide induction of a cytotoxic T lymphocyte response to HER-2/neu proto-oncogene in vitro.

The HER-2/neu proto-oncogene (HER-2) encodes a transmembrane protein whose expression is enhanced in a number of breast and ovarian tumors and correlates with tumor aggressiveness. Because of its expression on normal epithelial cells, HER-2 can be defined as a tumor associated antigen and is of interest as a target of a therapeutic anti-tumor T cell response. To investigate whether oligopeptides analogs of HER-2 isolated from a likely target area of T cells can induce an anti-tumor CTL response, peripheral blood mononuclear cells were stimulated in vitro with HER-2 synthetic peptides. CTL cultures generated recognized peptides used as immunogen. A CD3+CD8+CD4- line isolated from these cultures lysed HLA-A2+, HER-2+ ovarian tumors but not natural killer target K562 cells, and showed significantly higher lysis of HER-2high than of HER-2low ovarian tumors. This lysis was inhibited by HER-2 peptide-pulsed HLA-A2+ targets, suggesting that similar epitopes are presented on tumor cells associated with HLA-A2. The observation that peptide analogs of a proto-oncogene can induce CTL in vitro which express tumor lysis dependent on the levels of expression of HER-2 is novel for human tumor systems. Targeting by T cells of HER-2 may prove useful for understanding the mechanisms of recognition, tolerance, and therapeutic use of human tumor reactive T cells.

Amino Acid Sequence↗

PubMed1994

Characterization of T-cell receptor V beta repertoire in ovarian tumour-reacting CD3+ CD8+ CD4- CTL lines.

T cells from tumour infiltrating lymphocytes (TIL) cultured in media containing IL-2 were shown to mediate in vitro and in vivo antitumor responses. To characterize the T-cell antigen receptor (TCR) V beta expression in autologous cytotoxic effectors we isolated CD3+ CD8+ CD4- cells from cultures of TIL and tumour-associated lymphocytes (TAL) and analysed the TCR V beta repertoire of CD3+ CD8+ CD4- lines of known HLA-A, -B and -C phenotype, using polymerase chain reaction (PCR). These lines showed preferential lysis of autologous tumours and lysed, to a much lesser extent, NK and LAK cell-sensitive targets. Tumour lysis was inhibited by antibodies to CD3 and MHC class I antigens indicating that they are cytotoxic T lymphocytes (CTL). These CD8+ CTL lines expressed a broad distribution of TCR V beta repertoire which was dominated by particular groups of V beta families in each CTL line. However, no predominant expression of one or the same V beta segment in all CTL lines was observed although statistical correlations between V beta family usage and magnitude of the antitumour cytolytic response were found. These results suggest that certain TCR V beta families may be selected by antigen in ovarian tumour-reactive T cells and this selection may be affected by Ag expression, and/or host factors. To our knowledge, this is the first documentation of TCR V beta repertoire of human ovarian tumour-reactive CD3+ CD8+ CD4- CTL from different individuals of known HLA types.

Autoantigens↗

PubMed1994

Enhanced expression of HLA-A,B,C and inducibility of TAP-1, TAP-2, and HLA-A,B,C by interferon-gamma in a multidrug-resistant small cell lung cancer line.

Recent evidence suggests that deficient HLA Class I expression in SCLC lines may be due, in part, to down-regulation of TAP-1 and TAP-2 expression, and, thus, deficient antigen processing. Given the capability of the multidrug transporter mediating MDR, P-gp, to transport peptides, we hypothesized that P-gp may substitute for TAP-1/TAP-2 and enhance antigen processing in SCLC. To investigate this, we studied the H69 line (parent SCLC) and VPR-2 (MDR subline selected in etoposide, P-gp +). HLA-A,B,C expression was significantly increased in VPR-2 cells relative to H69, and was much more inducible with IFN-gamma. TAP-1 and TAP-2 were expressed at low levels in both lines. Differential induction of TAP-1 expression with IFN-gamma exposure was observed, with a dramatic increase in VPR-2 cells, and no change in H69. TAP-2 expression was enhanced in both lines with IFN-gamma, but to a greater degree in VPR-2. VPR-2 cells were resistant to LAK killing relative to H69, and were minimally sensitized with IFN-gamma. In contrast, IFN-gamma enhanced susceptibility of H69 to LAK killing 3-fold. The direct correlation between enhancement of HLA-A,B,C expression by IFN-gamma and the differential inducibility of TAP-1 and TAP-2 expression in P-gp-SCLC lines is novel. Relative LAK sensitivity of H69 and its increase by IFN-gamma may have clinical implications.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1993

Cytotoxic T cells isolated from ovarian malignant ascites recognize a peptide derived from the HER-2/neu proto-oncogene.

The HER-2/neu proto-oncogene encodes a transmembrane receptor protein whose expression is enhanced in a number of breast and ovarian tumors and correlates with tumor aggressiveness, suggesting that it may play an important role in tumor growth. Recent evidence suggests that HER-2/neu may be a potential candidate for targeted immune intervention. In this report we show that cytotoxic T lymphocytes (CTL) expanded from tumor-associated lymphocytes with HLA-A2+ and HER-2/neu+ tumors can specifically recognize synthetic peptides corresponding to amino acids 971-980 of HER-2/neu protein. This sequence includes a potential amphiphilic area containing both Rothbard's epitode motifs and HLA-A2 anchor residues. Our study provides the first direct evidence of HER-2/neu-reactive CTL in humans. The fact that these HER-2/neu peptide-reactive CTL show significantly lower reactivity with corresponding EGF-R peptides offers new perspectives for understanding the recognition of self-antigens by tumor-reactive T cells.

Amino Acid Sequence↗

PubMed1993

Cytotoxic T cells from ovarian malignant tumors can recognize polymorphic epithelial mucin core peptides.

CTL isolated from tumor infiltrating lymphocytes/tumor associated lymphocytes (TAL) infiltrating ovarian tumors have been demonstrated to mediate lysis of tumor targets after in vitro culture. These effector cells are of particular interest as cellular probes to detect and define human tumor Ag and epitopes that stimulate cellular immunity to human tumors. Polymorphic epithelial mucin (PEM) core peptides are potential candidates as tumor specific Ag because of their preferential expression on epithelial tumors. We report here that ovarian CTL-TAL can recognize mucin (Muc-1) core peptide of PEM. Several ovarian CTL-TAL lines were developed that recognized in a non-MHC restricted fashion an Muc-1+ ovarian tumor, but not Muc-1-tumor. To define the specificity of these CTL-TAL and exclude cross-reactivity with other potential Ag, cytotoxicity experiments were performed using as targets EBV-transformed cell lines with an expression construct containing the Muc.1 cDNA. These ovarian CTL-TAL lysed mucin core-peptide transfected cells but not targets transfected with an expression construct containing a mucin frame-shift mutant cDNA as control. In addition, targets pulsed with short synthetic peptides composed of amino acids 1-14 of the Muc 1 core peptide repeat were also lysed by the same CTL-TAL. This lysis was inhibited by the mAb SM3 that recognize an epitope on the mucin core peptide. These results, which are a demonstration of a specific Ag recognized by ovarian CTL-TAL, may be of interest for specific immunotherapy of ovarian cancer.

Amino Acid Sequence↗

PubMed1993

Cytotoxic T-cell clones isolated from ovarian tumour infiltrating lymphocytes recognize common determinants on non-ovarian tumour clones.

CTL-TIL lines have been developed from tumour infiltrating lymphocytes (TIL) from the ascites of patients with ovarian carcinoma, and used to investigate whether common tumour antigens are expressed on allogeneic ovarian tumours epithelial tumour lines derived from colon and pancreatic carcinoma. Three CTL lines expressed preferential cytolytic activity against autologous tumour cells and against certain allogeneic ovarian tumour cells that shared HLA-A2 molecules. Analysis of the target specificity of these CTL lines indicated that they also lysed human colon and pancreatic tumour lines sharing HLA-A2. CTL-TIL clones isolated from these lines were found to lyse HLA-A2+ ovarian, colon and pancreatic tumours, and to recognize clonally distributed common epitopes on pancreas and colon tumour clones. These results indicate that shared tumour antigens can be found among tumours of common epithelial cell origin. These results indicate a novel class of T-cell-definable tumour antigens recognized by tumour-reactive CTL on human tumours and may be significant for understanding of cellular immunity in ovarian cancer, identification of CTL-defined tumour antigens and future adoptive specific immunotherapeutic approaches in ovarian cancer.

Antigens, Neoplasm↗

PubMed1992

Induction of interleukin-2 receptor by tumor necrosis factor alpha on cultured ovarian tumor-associated lymphocytes.

We have recently reported that autologous tumor-specific cytotoxic T lymphocyte (CTL) lines and clones can be developed from lymphocytes infiltrating ovarian malignant ascites (TAL). In this study, we investigated the biological effects of tumor necrosis factor alpha (TNF alpha) in the induction, expansion, long-term proliferation and lytic function of CD8+ TAL. TNF alpha up-regulated the IL-2 receptor (IL-2R) alpha chain (Tac antigen) on the surface of CD3+ CD8+ CD4- TAL, enhanced the proliferation of autologous tumor-specific CTL, and potentiated their lytic function in long-term cultures. Furthermore, in the induction and expansion phase of CD8+ TAL, the presence of TNF alpha was associated with a selective increase in CD8+ IL-2R+ (Tac+) cells, and subsequent decrease in CD4+ IL-2R+ (Tac+) cells. These results suggest that the observed facilitation of the outgrowth of CD8+ cells in TAL cultures may be due, at least in part, to the up-regulation of IL-2R, and indicate the usefulness of TNF alpha in the analysis of signalling in autologous tumor-reactive CTL.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1991

Lymphocytes infiltrating ovarian malignant ascites: modulation of IL-2-induced proliferation by IL-4 and of selective increase in CD8+ T cells by TNF-alpha.

Lymphocytes infiltrating ovarian malignant ascites (TALs) were propagated in vitro in the presence of low (20-50 U/ml) concentrations of recombinant interleukin-2 (rIL-2) and moderate concentrations of interleukin-4 (IL-4) and tumor necrosis factor type alpha (TNF-alpha). Neither IL-4 nor TNF-alpha alone induced proliferation of ovarian TALs, but IL-4 and TNF-alpha synergized with IL-2 in enhancing the proliferation of T cells from cultures and inducing a more specific pattern of cytotoxic responses of ovarian TAL. IL-4 enhanced the proliferation of TAL cultures in the induction phase, but did not synergize with IL-2 in enhancing the proliferation and cytotoxicity of an established autologous tumor-specific CD8+/CD4- cytotoxic T lymphocyte (CTL) line. In contrast, TNF-alpha-induced preferential expansion of CD8+ CTL in TAL cultures where CD3+/CD4+ cells were initially in excess and of an established autologous tumor-specific CD8+ CTL line. This expansion resulted in increased levels of cytoxicity against autologous tumor cells. Amplification of IL-2 growth-promoting effects and selective enrichment in T cell subsets by IL-4 and TNF-alpha may therefore be useful in cellular adoptive immunotherapy using tumor-specific T cells.

Adenocarcinoma↗

PubMedDate not supplied

Existent proliferative responses of peripheral blood mononuclear cells from healthy donors and ovarian cancer patients to HER-2 peptides.

Identifying target antigens for tumor-reactive T cells is important for understanding the mechanisms of tumor escape and developing novel anticancer therapies. To date, mainly CTL responses from tumor infiltrating associated lymphocytes (TIL/TAL) to peptide antigens have been investigated in ovarian cancer. In the present study, the ability of self-peptides derived from HER-2/neu proto-oncogene product (HER-2) to stimulate proliferation of PBMC from healthy donors and ovarian cancer patients has been assessed. Peptide sequences from HER-2 containing anchors for major human MHC-class II molecules have been identified. These peptides induced proliferative and cytokine responses at higher frequency in healthy donors than ovarian cancer patients. Four HER-2 peptides corresponding to positions: 396-406, 474-487, 777-789, and 884-899 were able to stimulate proliferation of a larger number of healthy donors than three other distinct HER-2 peptides 449-464, 975-987 and 1086-1098. The pattern of responses of twenty five ovarian cancer patients was different from that in healthy donors. T cell lines were developed by stimulation with peptides from PBMC of an ovarian cancer patient who showed a stable response to all four HER-2 peptides for over six months. Each T cell line was different in its ability to secrete IFN-gamma and IL-10. These results demonstrate (a) that self-peptides from HER-2 can stimulate expansion of T cells in both healthy donors and ovarian cancer patients, and (b) the ability of different peptides to stimulate secretion of different cytokines from lymphocytes of ovarian cancer patients. These results may be important for understanding the mechanisms of tolerance and autoimmunity in human cancers.

Amino Acid Sequence↗