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  • 1
    ISSN: 1432-0851
    Schlagwort(e): TNFα ; CD8+ CTL ; IL-2R ; TIL/TAL
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 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 α (TNFα) in the induction, expansion, long-term proliferation and lytic function of CD8+ TAL. TNFα up-regulated the IL-2 receptor (IL-2R) α 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 TNFα 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 TNFα in the analysis of signalling in autologous tumor-reactive CTL.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0851
    Schlagwort(e): Key words Natural killer cells ; HER-2/neu ; Peptides ; MHC ; Tumor immunity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract 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.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-0851
    Schlagwort(e): Key words HER-2 ; Proliferation ; Th1 ; Cryptic determinants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Immunization with tumor antigens induces cellular and humoral immune responses. These responses by T cells are specific for defined epitopes (determinants) in the molecule of the immunizing tumor antigen. Extension of such responses to self-antigens requires induction of autoimmunity to the tumor. As with systems of autoimmune disease, expression of T cell autoimmunity is charaterized by diversification of responses from the inducer determinant to other responder (cryptic) determinants. Since similar strategies may be useful for therapy of human cancers, we investigated whether the induction of response to a HER-2 peptide F7 (776–789) induces enhanced reactivity of other HER-2 peptides. We found that stimulation with F7 can expand a response to another epitope F13 (884–899) in both an ovarian cancer patient with progressive disease and a healthy donor who shared HLA-DR11. This response was characterized mainly by increased interferon γ secretion, and proliferation, but was not observed with another donor who shared HLA-DR14 and HLA-DQ5 with the patient. Since repeated vaccination with the same epitope may lead to a decline of primary cell reactivity caused by apoptosis spreading the response to other epitopes, the tumor antigen may provide an approach for maintaining an inflammatory Th1 response during cancer vaccination.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1534-4681
    Schlagwort(e): CTL ; Peptide ; Vaccine ; Folate binding protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract 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.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The triphenylethylene antiestrogen trans-tamoxifen is an effective antitumor agent used in the treatment of human breast cancer. While the antiestrogenic activity of trans-tamoxifen clearly plays an important role in its tumoricidal action, some of the biological effects of trans-tamoxifen are independent of estrogen. Therapeutic concentrations of trans-tamoxifen inhibit protein kinase C (PKC) and calmodulin-dependent enzymes. PKC and calmodulin play critical roles in growth regulation, and there is evidence that inhibition of PKC and calmodulin by trans-tamoxifen may contribute to the antiumor activity of the drug in vivo.The geometric isomers cis- and trans-tamoxifen have a number of opposing biological activities that have been attributed to their interactions with the estrogen receptor, Cis-tamoxifen is generally estrogenic, whereas trans-tamoxifen is generally antiestrogenic. In this report, we compared the effects of cis- and trans-tamoxifen on PKC activity and on calmodulin-dependent cAMP phosphodiesterase activity. Cis- and trans-tamoxifen inhibited the Ca2+- and phosphatidylserine- (PS-) dependent activity of purified rat brain PKC with indistinguishable potencies, but cis-tamoxifen was somewhat more potent than the trans isomer in the inhibition of the Ca2+- and PS-independent activity of PKC. In addition, cis-tamoxifen was the more potent isomer in the inhibition of T lymphocyte activation, an event that entails a PKC-requiring signal transduction pathway. A modest preference of the cis isomer was also observed in the inhibition of a calmodulin-dependent cAMP phosphodiesterase. These results suggest a congruence between triphenylethylene binding sites on PKC and on the activated calmodulin-cAMP phosphodiesterase complex. We conclude that the interactions of cis- and trans-tamoxifen with PKC and the activated calmodulin-cAMP phosphodiesterase complex offer a criterion for distinguishing biological effects of triphenylethylenes that are due to interactions with the estrogen receptor from the biological effects resulting from their inhibitory activities against PKC and calmodulin-dependent processes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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