Monoclonal antibodies in the lymphatics: selective delivery to lymph node metastases of a solid tumor.

After subcutaneous injection, monoclonal antibodies directed against a tumor can enter local lymphatic vessels, pass to the draining lymph nodes, and bind to metastases there. Lymphatic delivery of antibody to early metastases is more efficient than intravenous administration, and the lymphatic route can be used to image smaller metastatic deposits. Perhaps more important, the lymphatic route minimizes binding of antibodies to circulating tumor antigens and to cross-reactive antigens present on normal tissues. Antibodies inappropriate for intravenous use because of binding to normal tissues may therefore be useful against lymph node metastases when injected subcutaneously or directly into lymphatic vessels.

Transformation by human papillomavirus 16 E6 and E7: role of the insulin-like growth factor 1 receptor.

Human papillomavirus-16 E6 and E7 inactivate the tumor suppressors p53 and pRB, respectively, and cooperate during malignant transformation, but the downstream molecular events remain incompletely understood. Using fibroblast cell lines derived from mice with a homozygous disruption of the insulin-like growth factor-1 receptor (IGF-1R) gene (R- cells) and their wild-type (WT) littermates, we have stably transfected plasmids encoding E6 and E7 proteins and examined their transforming potential in these cells. Consistent with previous studies using NIH3T3 cells, pooled cultures of E7-transfected WT cells readily formed colonies after suspension in soft agar. In contrast, R- cells were not transformed by E7. E6 had little transforming activity in WT (WT/E6) or R- (R-/E6) cells. However, transfection of R- cells with E6 plus E7 resulted in extensive colony formation. Because IGF-1R and E6 appear to be functionally equivalent in this transformation assay and both have been implicated in antiapoptotic responses, we investigated the apoptotic responses of the cells after exposure to the potent protein kinase C inhibitor, staurosporine. Compared to WT cells, R- cells were relatively resistant to staurosporine-induced apoptosis, but susceptibility to staurosporine was decreased in both WT/E6 and R-/E6 cells relative to WT and R- cells transfected with mock vector, respectively. In fibroblast cells from p53 gene knockout mice, transfection with E6 also conferred relative resistance to staurosporine-induced apoptosis. Our data suggest that transformation by E7 requires the participation of the IGF-1R and that E6 may assist E7 in transforming R- cells by functionally substituting for the IGF-1R. Because IGF-1R activated by its ligands (IGF-1 and IGF-2) protects cells from apoptosis, the role of the IGF-1R and E6 in transformation by E7 is probably related to the recruitment of survival pathways. In addition, because E6 suppressed apoptosis in p53 knockout cells, our data also suggest that E6 may participate in a p53-independent process that protects cells from apoptosis.

Overexpression of the insulin-like growth factor-1 receptor and autocrine stimulation in human cervical cancer cells.

We characterized mechanisms of growth control involving insulin-like growth factor-1 (IGF-1), IGF-2, and IGF-1 receptor (IGF-1R) by investigating their expression in human cervical cancer cell lines, primary cervical tumor cell cultures, and normal ectocervical epithelial cells maintained in short-term culture. By reverse transcription followed by PCR, IGF-1 mRNA was not detected in any of the cell lines, whereas IGF-2 mRNA transcripts were detected in all of them. Using the RNase protection assay, low levels of IGF-2 mRNA were also detected in all of the cervical cancer cell lines, primary cervical tumor cell cultures, and normal ectocervical cultures tested, but no IGF-1 transcripts were detected. Scatchard analysis revealed 3- and 5-fold increases in IGF-1R expression by the primary cervical cancer cell cultures and cervical cancer cell lines, respectively, compared with the normal ectocervical cells. In proliferation assays, epidermal growth factor (EGF) consistently enhanced cervical cancer cell growth, but an antisense oligonucleotide to IGF-2 uniformly inhibited the EGF-induced mitogenic effect. These studies suggest that autocrine production of IGF-2 and overexpression of the IGF-1R are important components controlling the proliferation of cervical carcinoma cells, and that autocrine IGF-2 production in cervical cancer cells may participate in the mitogenic signaling of EGF.

Induction of specific CD8+ T-lymphocyte responses using a human papillomavirus-16 E6/E7 fusion protein and autologous dendritic cells.

When intracellular viral proteins are degraded, only a limited number of peptide epitopes are capable of eliciting specific CD8+ cellular immune responses for a given human leukocyte antigen (HLA) haplotype. We sought to induce CD8+ T-lymphocyte (CTL) responses to human papillomavirus-16 (HPV-16) E6 and E7 proteins using a recombinant E6/E7 fusion protein and autologous human dendritic cells (DCs). CTLs were generated by in vitro stimulation using a recombinant HPV-16 E6/E7 fusion protein and autologous DCs from a healthy HLA-A*0201 donor. CTL specificity was assessed by cytokine release assays when the cells were reacted with autologous DC targets coincubated with the E6/E7 fusion protein. These CTLs were also reacted with the immunodominant E7 peptides (E711-20 and E7(86-93)) and DCs as a target. As a negative control, DCs were incubated with or without an irrelevant control protein (Helicobacter pylori) as target for the E6/E7-induced CTLs. The E6/E7-induced CTLs were capable of specific recognition of target DCs coincubated with E6/E7 but not the control protein. When E6/E7-specific CTLs were reacted with DCs and either E7(11-20) or E7(86-93), specific peptide recognition was also detected. These data demonstrate that specific CTLs can be elicited using autologous human DCs and a HPV-16 E6/E7 fusion protein. Therefore, extracellular viral proteins seem to be engulfed and processed by DCs; then the immunodominant HLA-A2-restricted peptides become available for CD8+ T-lymphocyte recognition. These data suggest that vaccine strategies using recombinant viral proteins may overcome the limitation of peptide epitopes for specific HLA haplotypes and may, therefore, permit more generalized clinical application.

Targeting of murine radiolabeled monoclonal antibodies in the lymphatics.

The tissue localization of a radiolabeled monoclonal antibody directed against a mouse Class I major histocompatibility antigen has been determined in mice following i.v. and s.c. administration. When labeled antibody was given s.c., radioactivity rapidly accumulated in regional lymph nodes draining the injection site, allowing visualization of the nodes by gamma camera imaging within minutes of injection. At 2 h after s.c. injection, radioactivity in regional nodes was present largely as intact antibody, but considerable degradation of antibody present in nodes was noted by 12 h after injection. Since little of the radioactivity reached the blood stream, visualization of regional nodes was possible for long periods after dosing. In contrast, antibody given i.v. showed no significant accumulation in lymph nodes at any time after dosing.

Optimization of monoclonal antibody delivery via the lymphatics: the dose dependence.

After interstitial injection in mice, antibody molecules enter local lymphatic vessels, flow with the lymph to regional lymph nodes, and bind to target antigens there. Compared with i.v. administration, delivery via the lymphatics provides a more efficient means for localizing antibody in lymph nodes. An IgG2a (36-7-5) directed against the murine class I major histocompatibility antigen H-2Kk has proved useful for studying the pharmacology of lymphatic delivery. The antibody specifically binds to most cells in Kk-positive strains of mice and to none in Kk-negative mice. At very low doses, most of the antibody remains at the injection site in Kk-positive animals. As the dose is progressively increased, most effective labeling occurs first in nodes proximal to the injection site and then in the next group of nodes along the lymphatic chain. At higher doses, antibody overflows the lymphatic system and enters the blood-stream via the thoracic duct and other lymphatic-venous connections. Once in the blood, antibody is rapidly cleared, apparently by binding to Kk-bearing cells. These findings indicate that the single-pass distribution of monoclonal antibodies in the lymphatics can be strongly dose dependent, a principle which may be of clinical significance in the improvement of immunolymphoscintigraphic imaging, especially with antibodies directed against normal and malignant lymphoid cells. Monoclonal antibodies directed against normal cell types in the lymph node may be useful for assessing the integrity of lymphatic chains by immunolymphoscintigraphy or, more speculatively, for altering the status of regional immune function. The results presented here indicate that a low or intermediate antibody dose may optimize the signal:noise ratio for imaging. In Kk-negative animals, the percentage of dose taken up in the major organs was essentially independent of the dose administered; there was no evidence for saturable sites of nonspecific binding. These findings provide background for attempts to use antitumor antibodies via the lymphatic route. Specific binding to target cells (and any cross-reaction with normal tissues) would presumably be superimposed on the nonspecific pharmacology of the antibody in vivo.

Cell-mediated immunological responses in cervical and vaginal cancer patients immunized with a lipidated epitope of human papillomavirus type 16 E7.

Human papillomavirus (HPV) infection has been causally associated with cervical cancer. We tested the effectiveness of an HLA-A*0201-restricted, HPV-16 E7 lipopeptide vaccine in eliciting cellular immune responses in vivo in women with refractory cervical cancer. In a nonrandomized Phase I clinical trial, 12 women expressing the HLA-A2 allele with refractory cervical or vaginal cancer were vaccinated with four E786-93 lipopeptide inoculations at 3-week intervals. HLA-A2 subtyping was also performed, and HPV typing was assessed on tumor specimens. Induction of epitope-specific CD8+ T-lymphocyte (CTL) responses was analyzed using peripheral blood leukapheresis specimens obtained before and after vaccination. CTL specificity was measured by IFN-gamma release assay using HLA-A*0201 matched target cells. Clinical responses were assessed by physical examination and radiographic images. All HLA-A*0201 patients were able to mount a cellular immune response to a control peptide. E786-93-specific CTLs were elicited in 4 of 10 evaluable HLA-A*0201 subjects before vaccination, 5 of 7 evaluable HLA-A*0201 patients after two vaccinations, and 2 of 3 evaluable HLA-A*0201 cultures after all four inoculations. Two of three evaluable patients' CTLs converted from unreactive to reactive after administration of all four inoculations. There were no clinical responses or treatment toxicities. The ability to generate specific cellular immune responses is retained in patients with advanced cervical cancer. Vaccination with a lipidated HPV peptide epitope appears capable of safely augmenting CTL reactivity. Although enhancements of cellular immune responses are needed to achieve therapeutic utility in advanced cervical cancer, this approach might prove useful in treating preinvasive disease.

Cytokine regulation of trophoblast steroidogenesis.

Activated monocytes and lymphocytes secrete cytokines that act as autocrine and paracrine mediators to promote and regulate local immune processes. These cell types are abundant at the maternal-fetal interface, and cytokines may play a role in pregnancy maintenance or failure. The purpose of this study was to determine the effects of selected monocyte- and lymphocyte-derived cytokines on trophoblast progesterone and estradiol production. JEG-3 choriocarcinoma cells were cultured in supplemented medium alone or in various concentrations of selected recombinant monocyte or lymphocyte cytokines. The cytokines were evaluated both individually and in combination. After 48 h of incubation, the culture supernatant was aspirated and stored at -20 C. Samples were then analyzed for steroid concentration by specific RIAs. Specific interleukin-1 (IL-1)-and tumor necrosis factor (TNF)-neutralizing antibodies were evaluated for their ability to abrogate the cytokine's observed stimulatory effect. To evaluate the physiological relevance of the progesterone-stimulating effect observed with monocyte-derived cytokines, JEG-3 cells were incubated with activated monocyte supernatant or directly cocultured with activated monocytes, and supernatants from these cultures were analyzed for progesterone levels. The monocyte cytokines [IL-1 alpha (5 U/mL), IL-1 beta (5 U/mL), and TNF alpha (1000 U/mL) significantly stimulated trophoblast progesterone production (nanograms per mL): JEG-3 control, 4.1 +/- 0.5; IL-1 alpha, 7.8 +/- 0.9; IL-1 beta, 8.8 +/- 0.5; and TNF alpha 7.2 +/- 0.8 (P < 0.05). Neither the monocyte nor the lymphocyte cytokines altered trophoblast estradiol production. Activated monocyte supernatant and direct JEG-3-monocyte cocultures also significantly stimulated trophoblast progesterone production in vitro. The stimulatory effect of the monocyte-derived cytokines was specific, as demonstrated by neutralization assay. The increased trophoblast progesterone production was not due to enhanced cellular proliferation, but to enhance cellular steroidogenesis, as measured by quantitative DNA analysis. The lymphocyte cytokines (IL-2, interferon-gamma, and granulocyte-macrophage colony-stimulating factor had no effect on trophoblast progesterone production. We conclude that monocyte IL-1 alpha, IL-1 beta, and TNF alpha may regulate trophoblast progesterone production through paracrine effects. Monocyte-trophoblast interactions may be significant in normal pregnancy as well as pregnancy disorders.

Human papillomavirus immunology and vaccine prospects.

As a result of several recent advances in molecular biology, the association between human papillomavirus (HPV) infection and cervical cancer has been firmly established and the oncogenic potential of certain HPV types has been clearly demonstrated. These observations provide the impetus for the development of novel vaccines to prevent or treat HPV-associated cervical cancer. Because there is no effective culturing system to propagate HPV, traditional approaches for studying HPV and developing vaccines have been hampered. However, recent studies using recombinant subunit preparations in animals have yielded promising results and encourage their investigation in human trials. Strategies currently under investigation focus on the induction of effective humoral immune responses for prophylaxis against subsequent HPV infection; for the treatment of existing HPV infections, techniques to improve cell-mediated immunity by enhancing viral antigen recognition are being studied. Small-scale human trials using several different vaccine approaches should be completed within the next few years and field trials of the most promising one(s) could begin within a decade. The development of successful therapeutic and/or prophylactic vaccines offers an attractive alternative to existing screening and treatment programs for cervical cancer and may result in a substantial reduction in the worldwide morbidity from this disease.

Natural history of twin pregnancy with complete hydatidiform mole and coexisting fetus.

OBJECTIVE: To investigate the clinical features and natural history of twin conceptions consisting of complete hydatidiform mole and a coexisting fetus. METHODS: Since 1973, eight well-documented cases of twin pregnancy with complete hydatidiform mole and coexisting fetus have been treated at the New England Trophoblastic Disease Center (NETDC). The clinical features of these eight patients were compared to 71 patients with singleton complete hydatidiform mole treated at the NETDC and with the published experience of other investigators. Flow cytometric analysis of DNA content was performed in addition to histologic inspection to assist in confirming the diagnosis of twin pregnancy with complete hydatidiform mole and coexisting fetus. RESULTS: Five of the eight patients in this series developed persistent gestational trophoblastic tumor requiring chemotherapy. Three of these five patients developed metastases requiring multi-agent chemotherapy to achieve remission. The presenting symptoms of twin pregnancy with complete hydatidiform mole and coexisting fetus were similar to those in patients with a singleton complete mole. However, compared to singleton complete molar gestation, a twin pregnancy with complete mole and coexisting fetus was diagnosed at a later gestational age, had higher preevacuation beta-hCG levels, and had a greater propensity to develop persistent gestational trophoblastic tumor. CONCLUSION: Our findings indicate that patients with complete hydatidiform mole and coexisting fetus are at high risk for developing persistent gestational trophoblastic tumor.

A pilot phase I trial of continuous hyperthermic peritoneal perfusion with high-dose carboplatin as primary treatment of patients with small-volume residual ovarian cancer.

PURPOSE: Because intraperitoneal (i.p.) therapy may provide a therapeutic advantage and because hyperthermia enhances carboplatin (CBDCA) cytotoxicity, we evaluated the feasibility, toxicity, and pharmacokinetics of CBDCA given via continuous hyperthermic peritoneal perfusion (CHPP) in patients with small-volume residual ovarian cancer. PATIENTS AND METHODS: Six patients underwent optimal cytoreductive procedures (residual disease < or =5 mm) as initial treatment of stages II and III epithelial ovarian adenocarcinoma. All patients received a 90-min CHPP at a CBDCA dose of 800-1200 mg/m2, with the perfusate being recirculated rapidly from a reservoir through a heat exchanger, resulting in i.p. temperatures of 41-43 degrees C. Plasma, perfusate, and urine samples were collected and platinum was quantified by flameless atomic absorption spectrophotometry. RESULTS: At no time did any patient's core temperature exceed 40 degrees C. Peak perfusate platinum concentrations were 8- to 15-fold higher than peak ultrafilterable plasma concentrations. The permeability-area product was extremely high and variable (14-90 ml/min), resulting in a regional advantage of 1.9-5.3. The percentage of the dose absorbed ranged widely from 27% to 77%. Dose-limiting hematologic toxicity was observed at a dose of 1200 mg/m2 and this was associated with a CBDCA AUC in plasma of 11 mg min ml(-1). CONCLUSION: CHPP with CBDCA was safely given to three patients at a dose of 800 mg/m2, and dose-limiting hematologic toxicities observed at 1200 mg/m2, correlated with the plasma CBDCA exposure established when lower doses of CBDCA are given systemically. The pharmacokinetic data are consistent with the expected effect of vigorous mixing on the exposed peritoneal surface area. Variable drug absorption and clearance make the prediction of systemic exposure highly uncertain. These findings may have important implications for novel therapies given i.p.

Insulin-like growth factor-II participates in the biphasic effect of a gonadotropin-releasing hormone agonist on ovarian cancer cell growth.

OBJECTIVE: To examine the involvement of insulin-like growth factors (IGFs) in growth regulation of an ovarian cancer cell line and to investigate whether the GnRH agonist tryptorelin might influence a potential autocrine or paracrine loop involving IGFs. DESIGN: In vitro, prospective, randomized controlled study. SETTING: In vitro experiments at the Section of Gynecologic Oncology, Surgery Branch, National Cancer Institute. PATIENT(S): None. Human ovarian adenocarcinoma cell line IGROV-1. INTERVENTION(S): The proliferative effect of tryptorelin on IGROV-1 cells was analyzed by using the MTT (93-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide) colorimetric assay. The ribonuclease protection assay was used to investigate whether an autocrine pathway involving IGF-I or IGF-II might participate in the growth of these cells. The expression of GnRH receptor was assessed by the 125I-GnRH binding assay. MAIN OUTCOME MEASURE(S): Changes in cell growth and expression of IGF-I and IGF-II messenger RNA (mRNA). RESULT(S): Tryptorelin exhibited a bimodal, dose- and time-dependent effect on IGROV-1 cells when compared with untreated control cells: Cellular proliferation was enhanced during the first 24 hours of exposure, but longer incubations resulted in growth inhibition. The mitogenic effect of tryptorelin was inhibited when cells were co-incubated with either IGF binding protein-5 (IGFBP-5) or anti-IGF-II antibody, which can both bind to IGF-II and neutralize it. Insulin-like growth factor-I mRNA was not detected in IGROV-1 cells. However, IGF-II transcripts were detected after incubation with tryptorelin for 12 hours, but thereafter, no mRNA was observed, even after prolonged exposure. Binding analysis revealed a specific, high-affinity GnRH binding site. CONCLUSION(S): These data suggest that tryptorelin exerts a bimodal growth effect on ovarian cancer cells by a mechanism involving the autocrine production of IGF-II. The effect of tryptorelin on IGF-II gene transcription in these ovarian cancer cells appears to mirror the desensitizing effects of prolonged GnRH exposure on pituitary gonadotropin production.

Progress and prospects in vaccine therapy for gynecologic cancers.

Therapeutic and prophylactic vaccines that harness the potential of the immune system against a number of gynecologic cancers are now being developed. The therapeutic vaccines coerce the cellular components of the immune system to attack malignant tissue. The prophylactic vaccines induce the production of antibodies capable of neutralizing viral antigens before they infect host cells. However, malignant tumors are usually a heterogeneous mixture of different malignant cells, and it is likely that variant tumor clones within a tumor may not express the target antigen or may possess defects in their antigen-presenting mechanism. Ultimately, therapeutic vaccines may be better suited for the treatment of preinvasive disease or for use as an adjuvant following primary therapy. The prospects for developing efficacious vaccines to treat or prevent cervical, ovarian, uterine, and other gynecologic cancers are promising, however. This article describes the methodology of and rationale for these vaccines.

Effects of cytokines on epidermal growth factor receptor expression by malignant trophoblast cells in vitro.

Trophoblastic cells abundantly express epidermal growth factor (EGF) receptors, which, when activated by EGF or transforming growth factor-alpha, can influence cellular growth and metabolism. Various lymphocyte and macrophage cytokines have been found to influence the proliferation of human choriocarcinoma (CCA) cells in vitro. In the current study we investigated the possibility that certain cytokine effects are mediated by changes in EGF receptor expression. JEG-3 human CCA cells were incubated with varying concentrations of interleukin 1-alpha (IL-1 alpha), interleukin 1-beta (IL-1 beta), interleukin 2, gamma-interferon, granulocyte-macrophage colony stimulating factor and tumor necrosis factor-alpha (TNF), and the expression of EGF receptor was measured by radioimmunoassay using a murine monoclonal antibody with specificity for the EGF receptor. Proliferative or growth suppressive effects of the cytokines were assessed by quantitative analysis of the DNA in the cell culture wells. Macrophage-derived cytokines IL-1 alpha, IL-1 beta and TNF significantly suppressed cell growth; this was associated with a significant increase in EGF receptor expression. The other cytokines had no significant effect on either EGF receptor expression or cell growth. We also studied the expression of EGF mRNA in JEG-3, Jar and BeWo CCA cell lines. By reverse transcription followed by polymerase chain reaction, low levels of EGF mRNA were detected in all three cell lines. Therefore, EGF may be synthesized by JEG-3, Jar and BeWo CCA cell lines to participate in an autocrine growth pathway. Our findings support the concept that cytokines may act as paracrine mediators of autocrine processes involved in CCA cell growth regulation by modulating growth factor receptor expression.

Clinical features of multiple conception with partial or complete molar pregnancy and coexisting fetuses.

The estimated incidence of twin pregnancy consisting of hydatidiform mole and a coexisting fetus is 1 per 22,000-100,000 pregnancies. Since 1965, nine patients with this entity have been treated at the New England Trophoblastic Disease Center (NETDC), Boston. One patient had a partial hydatidiform mole coexisting with a normal placenta and fetus. The other eight patients had twin pregnancies with a complete hydatidiform mole (CHM) and coexisting fetus. We compared the clinical outcomes in these 8 patients and 14 additional published case reports of multiple gestations composed of CHM and coexisting fetuses with a group of 71 patients with singleton CHM treated at NETDC. Twelve of the 22 patients (55%) with CHM and coexisting fetuses developed persistent gestational trophoblastic tumor, requiring chemotherapy. Five of these patients developed metastases requiring multiple cycles of chemotherapy to achieve remission. The presenting symptoms of multiple conception with CHM and coexisting fetuses were similar to those in patients with a singleton conception and complete mole. However, as compared to singleton CHM, patients having a multiple conception with CHM and coexisting fetuses were diagnosed at a later gestational age, had higher preevacuation beta-human chorionic gonadotropin levels and had a greater propensity to develop persistent tumor. These data indicate that patients with multiple conceptions consisting of CHM and coexisting fetuses are at high risk of developing persistent gestational trophoblastic tumor.

Insulin-like growth factor II mediates epidermal growth factor-induced mitogenesis in cervical cancer cells.

There is increasing evidence that activation of the insulin-like growth factor I (IGF-I) receptor plays a major role in the control of cellular proliferation of many cell types. We studied the mitogenic effects of IGF-I, IGF-II, and epidermal growth factor (EGF) on growth-arrested HT-3 cells, a human cervical cancer cell line. All three growth factors promoted dose-dependent increases in cell proliferation. In untransformed cells, EGF usually requires stimulation by a "progression" factor such as IGF-I, IGF-II, or insulin (in supraphysiologic concentrations) in order to exert a mitogenic effect. Accordingly, we investigated whether an autocrine pathway involving IGF-I or IGF-II participated in the EGF-induced mitogenesis of HT-3 cells. With the RNase protection assay, IGF-I mRNA was not detected. However, IGF-II mRNA increased in a time-dependent manner following EGF stimulation. The EGF-induced mitogenesis was abrogated in a dose-dependent manner by IGF-binding protein 5 (IGFBP-5), which binds to IGF-II and neutralizes it. An antisense oligonucleotide to IGF-II also inhibited the proliferative response to EGF. In addition, prolonged, but not short-term, stimulation with EGF resulted in autophosphorylation of the IGF-I receptor, and coincubations with both EGF and IGFBP-5 attenuated this effect. These data demonstrate that autocrine secretion of IGF-II in HT-3 cervical cancer cells can participate in EGF-induced mitogenesis and suggest that autocrine signals involving the IGF-I receptor occur "downstream" of competence growth factor receptors such as the EGF receptor.

Human papillomavirus vaccines for cervical cancer.

Cervical cancer is one of the most common causes of cancer-related death in women. As a result of several recent advances in molecular biology, the association between human papillomavirus (HPV) infection and cervical cancer has been firmly established, and the oncogenic potential of certain HPV types has been clearly demonstrated. Several lines of evidence suggest the importance of the host's immune response, especially cellular immune response, in the pathogenesis of HPV-associated cervical lesions. These observations form a compelling rationale for the development of vaccine therapy to combat HPV infection. Both prophylactic and therapeutic HPV vaccine strategies are being developed. Prophylactic strategies currently under investigation focus on the induction of effective humoral immune responses against subsequent HPV infection. In this respect, impressive immunoprophylactic effects have been demonstrated in animals using papillomavirus-like particles (VLPs). VLPs are antigenic and protective, but are devoid of any viral DNA that may be carcinogenic to the host. For treatment of existing HPV infection, techniques to improve cellular immunity by enhancing viral antigen recognition are being studied. For this purpose, the oncogenic proteins E6 and E7 of HPV-16 and -18 are the focus of current clinical trials for cervical cancer patients. The development of successful HPV-specific vaccines may offer an attractive alternative to existing screening and treatment programs for cervical cancer.

Interferon-gamma receptors on human gestational choriocarcinoma cell lines: quantitative and functional studies.

OBJECTIVES: This study was performed to further define the effects of interferon-gamma on choriocarcinoma cell lines and to determine whether variations in response among cell lines are attributable to quantitative differences in interferon-gamma receptors. STUDY DESIGN: Interferon-gamma receptors were quantified on BeWo, JEG-3 and Jar choriocarcinoma cell lines by a radiolabeled interferon-gamma ligand binding assay. The response of these cell lines to interferon-gamma was measured in two functional assays: a cell proliferation assay and a cell lysis assay after exposure to interferon-gamma with and without actinomycin-D. RESULTS: The number of interferon-gamma receptors on BeWo, Jar, and JEG-3 cells did not differ significantly (650, 560, and 420 interferon-gamma receptors per cell, respectively). Proliferation of all three choriocarcinoma cell lines was significantly inhibited to a similar extent by interferon-gamma. After treatment with interferon-gamma actinomycin-D, each choriocarcinoma cell line exhibited dose-dependent cell lysis; lysis of Jar was significantly less than that of either BeWo or JEG-3. CONCLUSION: These data further document variations in the response of choriocarcinoma cell lines to interferon-gamma and indicate that these differences are not the result of interferon-gamma receptor number but of postreceptor mechanisms.

Molar villous fluid suppresses mononuclear cell cytotoxicity.

Complete molar pregnancy tissue is an allograft to the mother because all molar chromosomes are of paternal origin. Interactions between molar tissue and the maternal immune system may be important in the natural history of complete molar pregnancy. Molar villous fluid (MVF) has previously been demonstrated to suppress both mitogen and interleukin-2-induced T lymphocyte proliferation. The current study was undertaken to evaluate the potential effect of MVF on the cytotoxic activity of mononuclear cells (MNC) and lymphokine-activated mononuclear cells (LA-MNC). Sera and molar villous fluid were obtained from four women at the time of molar evacuation. K-562 erythroblastoid cells were used as target cells for MNC-mediated lysis, and JEG-3 choriocarcinoma cells were used as targets for LA-MNC-mediated lysis in a 51Cr release assay. Relative to patient sera, all MVF tested significantly inhibited both MNC and LA-MNC lysis of target cells (48.3 and 91% mean inhibition, respectively; P < 0.05). This study provides additional evidence that molar gestational tissue produces factor(s) that suppress maternal immunologic responses. Potential therapies may become available to reduce or eliminate the immunosuppressive effects of molar gestations resulting in a more favorable clinical outcome in patients with complete molar pregnancy and postmolar gestational trophoblastic tumors.

Generation of tumor-specific cytolytic T lymphocytes from peripheral blood of cervical cancer patients by in vitro stimulation with a synthetic human papillomavirus type 16 E7 epitope.

OBJECTIVE: Approximately 90% of squamous carcinomas of the cervix harbor the human papillomavirus and type 16 has been detected in nearly 50% of cases. Recent studies in mice have shown that the human papillomavirus type 16 E7 oncoprotein contains peptide epitopes that are processed and presented in association with a major histocompatibility antigen for recognition by cytolytic T lymphocytes. We investigated whether an epitope from human papillomavirus type 16 E7 could be used to generate specific human cytolytic T lymphocytes in patients with cervical carcinoma. STUDY DESIGN: After radiation therapy, three patients with antigen HLA-A2 and with locally advanced cervical cancer underwent leukapheresis. Epitope-specific cytolytic T lymphocytes were generated from the peripheral blood mononuclear cells by in vitro stimulation with autologous peripheral blood mononuclear cells pulsed with a human papillomavirus type 16 E7, HLA-A2-restricted, synthetic peptide, E7(11-20) (YMLDLQPETT). RESULTS: In two patients cytolytic T lymphocytes were capable of E7(11-20)-specific, HLA-A2-restricted cytolysis of the peptide-pulsed, HLA-matched, T2 target cell line. Cytolytic T lymphocytes from one of these patients also demonstrated specific cytolysis against the HLA-A2+, HPV-16+ CaSki cervical cancer cell line but did not lyse either HLA-A2+, HPV-16- MS-751 cells or HLA-A2-, HPV-16- HT-3 cells. CONCLUSIONS: These experiments demonstrate that novel cytolytic T lymphocytes that recognize a human papillomavirus type 16 E7 epitope can be generated by using the peripheral blood mononuclear cells from irradiated patients with cervical cancer. In addition, because CaSki cells were specifically lysed by the cytolytic T lymphocytes, these data indicate that the peptide E7(11-20) is endogenously processed and presented on the cell surface of the CaSki cells. The demonstration of epitope-specific lysis of cytolytic T lymphocytes of HPV-16+ cervical cancer cells supports further efforts to develop human papillomavirus peptide-based vaccines or antigen-specific adoptive immunotherapy for the prevention and treatment of cervical carcinoma.