Memory T cells specific for novel human papillomavirus type 16 (HPV16) E6 epitopes in women whose HPV16 infection has become undetectable

Design and evaluation of a multi-epitope DNA vaccine against HPV16

Cervical cancer, among the deadliest cancers affecting women globally, primarily arises from persistent infection with high-risk human papillomavirus (HPV). To effectively combat persistent infection and prevent the progression of precancerous lesions into malignancy, a therapeutic HPV vaccine is under development. This study utilized an immunoinformatics approach to predict epitopes of cytotoxic T lymphocytes (CTLs) and helper T lymphocytes (HTLs) using the E6 and E7 oncoproteins of the HPV16 strain as target antigens. Subsequently, through meticulous selection of T-cell epitopes and other necessary elements, a multi-epitope vaccine was constructed, exhibiting good immunogenic, physicochemical, and structural characteristics. Furthermore, in silico simulations showed that the vaccine not only interacted well with toll-like receptors (TLR2/TLR3/TLR4), but also induced a strong innate and adaptive immune response characterized by elevated Th1-type cytokines, such as interferon-gamma (IFN-γ) and interleukin-2 (IL2). Additionally, our study investigated the effects of different immunization intervals on immune responses, aiming to optimize a time-efficient immunization program. In animal model experiments, the vaccine exhibited robust immunogenic, therapeutic, and prophylactic effects. Administered thrice, it consistently induced the expansion of specific CD4 and CD8 T cells, resulting in substantial cytokines release and increased proliferation of memory T cell subsets in splenic cells. Overall, our findings support the potential of this multi-epitope vaccine in combating HPV16 infection and signify its candidacy for future HPV vaccine development.

The common HLA class I-restricted tumor-infiltrating T cell response in HPV16-induced cancer

Immunotherapies targeting truly tumor-specific targets focus on the expansion and activation of T cells against neoantigens or oncogenic viruses. One target is the human papilloma virus type 16 (HPV16), responsible for several anogenital cancers and oropharyngeal carcinomas. Spontaneous and vaccine-induced HPV-specific T cells have been associated with better clinical outcome. However, the epitopes and restriction elements to which these T cells respond remained elusive. To identify CD8+ T cell epitopes in cultures of tumor infiltrating lymphocytes, we here used multimers and/or a functional screening platform exploiting single HLA class I allele-engineered antigen presenting cells. This resulted in the detection of 20 CD8+ T cell responses to 11 different endogenously processed HLA-peptide combinations within 12 HPV16-induced tumors. Specific HLA-peptide combinations dominated the response in patients expressing these HLA alleles. T cell receptors (TCRs) reactive to seven different HLA class I-restricted peptides could be isolated and analysis revealed tumor reactivity for five of the six TCRs analyzed. The tumor reactive TCRs to these dominant HLA class I peptide combinations can potentially be used to engineer tumor-specific T cells for adoptive cell transfer approaches to treat HPV16-induced cancers.

Effect of Multiple Vaccinations with Tumor Cell-Based Vaccine with Codon-Modified GM-CSF on Tumor Growth in a Mouse Model

Ectopic expression of codon-modified granulocyte-macrophage colony-stimulating factor (cGM-CSF) in TC-1 cells (TC-1/cGM-CSF), a model cell line for human papillomavirus (HPV)-infected cervical cancer cells, increased the expression level of GM-CSF and improved the efficacy of tumor cell-based vaccines in a cervical cancer mouse model. The number of vaccine doses required to induce a long-term immune response in a cervical cancer mouse model is poorly understood. Here, we investigated one, three, and five doses of the irradiated TC-1/cGM-CSF vaccine to determine which dose was effective in inducing a greater immune response and the suppression of tumors. Our findings showed that three doses of irradiated TC-1/cGM-CSF vaccine elicited slower tumor growth rates and enhanced survival rates compared with one dose or five doses of irradiated TC-1/cGM-CSF vaccine. Consistently, mice vaccinated with three doses of irradiated TC-1/cGM-CSF vaccine exhibited stronger interferon gamma (IFN-γ) production in HPV E7-specific CD8⁺ T cells and CD4⁺ T cells. A higher percentage of natural killer cells and interferon-producing killer dendritic cells (IKDCs) appeared in the splenocytes of the mice vaccinated with three doses of irradiated TC-1/cGM-CSF vaccine compared with those of the mice vaccinated with one dose or five doses of irradiated TC-1/cGM-CSF vaccine. Our findings demonstrate that single or multiple vaccinations, such as five doses, with irradiated TC-1/cGM-CSF vaccine suppressed the immune response, whereas three doses of irradiated TC-1/cGM-CSF vaccine elicited a greater immune response and subsequent tumor suppression.

Photothermal therapy enhanced the effectiveness of imiquimod against refractory cutaneous warts through boosting immune responses

Refractory cutaneous warts are difficult to eliminate. In situ photo-immunotherapy (ISPI) is an innovative treatment concept combining local photothermal therapy (PTT) and topical immunotherapy using imiquimod. To compare the efficacy of ISPI vs topical imiquimod alone, a prospective randomized controlled trial was performed with patients suffering from refractory cutaneous warts. In both groups, approximately 50% of the skin surface containing warts was treated for 6 weeks. On the basis of topical imiquimod, ISPI includes an additional 808 nm laser irradiation. Treatment response, temperatures during irradiation and histopathologic examination were evaluated. The complete response rate in the ISPI-group (22/36, 61.1%) was significantly higher than in the imiquimod alone group (11/34, 32.4%). In the ISPI-group, the mean maximum temperature was 44.5 ± 5.1°C, and obvious lymphocytic infiltration was found in the perivasculature of the dermis. There was no recurrence or worsening in both groups during the 12-month follow-up. No obvious adverse reaction was observed. This study demonstrates that ISPI can be used as an effective and safe treatment modality for refractory cutaneous warts.

A novel prostate cancer immunotherapy using prostate-specific antigen peptides and Candida skin test reagent as an adjuvant

OBJECTIVES

Our group developed the use of the Candida skin test reagent as an adjuvant of cell-mediated immunity in designing a human papillomavirus therapeutic vaccine. Here, this technology is being applied for designing a prostate cancer immunotherapy.

METHODS

Peptides based on the prostate-specific antigen amino acid sequences were selected, synthesized, and evaluated in terms of their (1) solubility, (2) maturation effects on Langerhans cells by fluorescence-activated cell sorter analysis, and (3) recognition by peripheral immune cells from prostate cancer patients using interferon-γ enzyme-linked immunospot assay.

RESULTS

The peptides were soluble in 10 mM succinate at pH of 5 with 5% glycine, and they demonstrated no maturation effects on Langerhans cells from healthy donors. On the other hand, peripheral immune cells from 4 of 10 prostate cancer patients examined had positive responses in enzyme-linked immunospot assay to one or more prostate-specific antigen peptides.

CONCLUSION

In summary, a design and a formulation of a novel prostate cancer immunotherapy are described. The immunogenicity of prostate-specific antigen peptides in some prostate cancer patients supports further development of this immunotherapy.

A phase I dose-escalation clinical trial of a peptide-based human papillomavirus therapeutic vaccine with Candida skin test reagent as a novel vaccine adjuvant for treating women with biopsy-proven cervical intraepithelial neoplasia 2/3

PURPOSE: Non-surgical treatments for cervical intraepithelial neoplasia 2/3 (CIN2/3) are needed as surgical treatments have been shown to double preterm delivery rate. The goal of this study was to demonstrate safety of a human papillomavirus (HPV) therapeutic vaccine called PepCan, which consists of four current good-manufacturing production-grade peptides covering the HPV type 16 E6 protein and Candida skin test reagent as a novel adjuvant. PATIENTS AND METHODS: The study was a single-arm, single-institution, dose-escalation phase I clinical trial, and the patients (n = 24) were women with biopsy-proven CIN2/3. Four injections were administered intradermally every 3 weeks in limbs. Loop electrical excision procedure (LEEP) was performed 12 weeks after the last injection for treatment and histological analysis. Six subjects each were enrolled (50, 100, 250, and 500 μg per peptide). RESULTS: The most common adverse events (AEs) were injection site reactions, and none of the patients experienced dose-limiting toxicities. The best histological response was seen at the 50 μg dose level with a regression rate of 83% (n = 6), and the overall rate was 52% (n = 23). Vaccine-induced immune responses to E6 were detected in 65% of recipients (significantly in 43%). Systemic T-helper type 1 (Th1) cells were significantly increased after four vaccinations (P = 0.02). CONCLUSION: This study demonstrated that PepCan is safe. A significantly increased systemic level of Th1 cells suggests that Candida, which induces interleukin-12 (IL-12) in vitro, may have a Th1 promoting effect. A phase II clinical trial to assess the full effect of this vaccine is warranted.

Cross-Reactivity, Epitope Spreading, and De Novo Immune Stimulation Are Possible Mechanisms of Cross-Protection of Nonvaccine Human Papillomavirus (HPV) Types in Recipients of HPV Therapeutic Vaccines

Numerous versions of human papillomavirus (HPV) therapeutic vaccines designed to treat individuals with established HPV infection, including those with cervical intraepithelial neoplasia (CIN), are in development because approved prophylactic vaccines are not effective once HPV infection is established. As human papillomavirus 16 (HPV-16) is the most commonly detected type worldwide, all versions of HPV therapeutic vaccines contain HPV-16, and some also contain HPV-18. While these two HPV types are responsible for approximately 70% of cervical cancer cases, there are other high-risk HPV types known to cause malignancy. Therefore, it would be of interest to assess whether these HPV therapeutic vaccines may confer cross-protection against other high-risk HPV types. Data available from a few clinical trials that enrolled subjects with CINs regardless of the HPV type(s) present demonstrated clinical responses, as measured by CIN regression, in subjects with both vaccine-matched and nonvaccine HPV types. The currently available evidence demonstrating cross-reactivity, epitope spreading, and de novo immune stimulation as possible mechanisms of cross-protection conferred by investigational HPV therapeutic vaccines is discussed.

A Human Papillomavirus Type 16 E6 52-62 CD4 T-Cell Epitope Restricted by the HLA-DR11 Molecule Described in an Epitope Hotspot

Cell-mediated immune responses to the human papillomavirus type 16 (HPV 16) E6 protein have been shown to be important in viral clearance and in regression of cervical lesions. Here, detailed analyses of a novel HPV 16 E6 CD4 T-cell epitope from a subject with cervical intraepithelial neoplasia 1 are described. This subject had demonstrated HPV 16 CD4 T-cell responses to multiple regions within the E6 protein. Isolation and cloning of CD4 T-cells were performed by magnetic selection of interferon-γ secreting cells and limiting dilution. A single HPV 16-specific T-cell clone isolated was shown to have a specificity to HPV 16 E6 52-62 restricted by the HLA-DR11 molecule. Homologous sequences (≥70% amino acid homology) were identified for HPV types 31, 33, 45, 58, 73, but cross-recognition was demonstrated only for HPV 45. Based on work performed by our group and others, it is known that this short peptide contains multiple CD4 and CD8 T-cell HPV epitopes and would be an ideal region to incorporate into a design of vaccines and immunotherapies against HPV-associated malignancies.

Human papillomavirus type 16 E6/E7-specific cytotoxic T lymphocytes for adoptive immunotherapy of HPV-associated malignancies

Vaccines prevent human papillomavirus (HPV)-associated cancer but, although these tumors express foreign, viral antigens (E6 and E7 proteins), they have little benefit in established malignancies, likely due to negative environmental cues that block tumor recognition and induce T-cell anergy in vivo. We postulated that we could identify mechanisms by which ex vivo stimulation of T cells could reactivate and expand tumor-directed T-cell lines from HPV cancer patients for subsequent adoptive immunotherapy. A total of 68 patients with HPV-associated cancers were studied. Peripheral blood T cells were stimulated with monocyte-derived dendritic cells loaded with pepmixes [peptide libraries of 15-mers overlapping by 11 amino acids (aa)] spanning E6/E7, in the presence or absence of specific accessory cytokines. The resulting T-cell lines were further expanded with pepmix-loaded activated B-cell blasts. Interferon-γ release and cytotoxic responses to E6/E7 were assessed. We successfully reactivated and expanded (>1200-fold) E6-specific/E7-specific T cells from 8/16 cervical and 33/52 oropharyngeal cancer patients. The presence of the cytokines interleukin (IL)-6, IL-7, IL-12, and IL-15 is critical for this process. These T-cell lines possess the desirable characteristics of polyclonality, multiple T-cell subset representation (including the memory compartment) and a TH1 bias, and may eliminate E6/E7 targets. In conclusion, we have shown it is possible to robustly generate HPV16 E6/E7-directed T-cell lines from patients with HPV16-associated cancers. Because our technique is scalable and good-manufacturing procedures-compliant, these lines could be used for adoptive cellular immunotherapy of patients with HPV16 cancers.

Use of interferon-γ enzyme-linked immunospot assay to characterize novel T-cell epitopes of human papillomavirus

A protocol has been developed to overcome the difficulties of isolating and characterizing rare T cells specific for pathogens, such as human papillomavirus (HPV), that cause localized infections. The steps involved are identifying region(s) of HPV proteins that contain T-cell epitope(s) from a subject, selecting for the peptide-specific T cells based on interferon-γ (IFN-γ) secretion, and growing and characterizing the T-cell clones (Fig. 1). Subject 1 was a patient who was recently diagnosed with a high-grade squamous intraepithelial lesion by biopsy and underwent loop electrical excision procedure for treatment on the day the T cells were collected(1). A region within the human papillomavirus type 16 (HPV 16) E6 and E7 proteins which contained a T-cell epitope was identified using an IFN- g enzyme-linked immunospot (ELISPOT) assay performed with overlapping synthetic peptides (Fig. 2). The data from this assay were used not only to identify a region containing a T-cell epitope, but also to estimate the number of epitope specific T cells and to isolate them on the basis of IFN- γ secretion using commercially available magnetic beads (CD8 T-cell isolation kit, Miltenyi Biotec, Auburn CA). The selected IFN-γ secreting T cells were diluted and grown singly in the presence of an irradiated feeder cell mixture in order to support the growth of a single T-cell per well. These T-cell clones were screened using an IFN- γ ELISPOT assay in the presence of peptides covering the identified region and autologous Epstein-Barr virus transformed B-lymphoblastoid cells (LCLs, obtained how described by Walls and Crawford)(2) in order to minimize the number of T-cell clone cells needed. Instead of using 1 x 10(5) cells per well typically used in ELISPOT assays(1,3), 1,000 T-cell clone cells in the presence of 1 x 10(5) autologous LCLs were used, dramatically reducing the number of T-cell clone cells needed. The autologous LCLs served not only to present peptide antigens to the T-cell clone cells, but also to keep a high cell density in the wells allowing the epitope-specific T-cell clone cells to secrete IFN-γ. This assures successful performance of IFN-γ ELISPOT assay. Similarly, IFN- γ ELISPOT assays were utilized to characterize the minimal and optimal amino acid sequence of the CD8 T-cell epitope (HPV 16 E6 52-61 FAFRDLCIVY) and its HLA class I restriction element (B58). The IFN- γ ELISPOT assay was also performed using autologous LCLs infected with vaccinia virus expressing HPV 16 E6 or E7 protein. The result demonstrated that the E6 T-cell epitope was endogenously processed. The cross-recognition of homologous T-cell epitope of other high-risk HPV types was shown. This method can also be used to describe CD4 T-cell epitopes(4).

Biomarkers of oxidant load and type-specific clearance of prevalent oncogenic human papillomavirus infection: markers of immune response?

Human papillomavirus (HPV) infection is the cause of cervical cancer. Increased production of reactive oxygen species (ROS) maybe the common mechanism through which HPV-cofactors (i.e., smoking and inflammation) influence duration of infections. Biomarkers of total oxidant load may serve as cumulative measures of ROS exposure due to these cofactors. Therefore, we conducted a study evaluating the association between biomarkers of oxidant load and duration of HPV infections, early HPV natural history events. Serum samples were obtained from 444 HPV-positive women in the Ludwig-McGill Cohort Study. Anti-5-hydroxymethyl-2'-deoxyuridine autoantibody (anti-HMdU aAb) and malondialdehyde (MDA) were measured at baseline. Cox-proportional hazard models were used to estimate the probability of clearing any HPV, oncogenic HPV, non-oncogenic HPV and HPV-16 infections. Women with elevated MDA were significantly more likely to clear prevalent oncogenic HPV infections compared to those with lower MDA levels (Adjusted Hazard Ratio (AHR) = 2.7; 95%CI = 1.4-5.1). There did not appear to be an association between elevated MDA and clearance of incident oncogenic HPV infections. Similarly, women with elevated anti-HMdU aAb levels had higher rates of prevalent oncogenic HPV infection clearance (Quartile 3:AHR = 2.2; 95%CI = 1.2-4.4; Quartile 4:AHR = 2.4; 95%CI = 1.2-4.9). Higher levels of oxidant load biomarkers were associated with increased clearance of prevalent HPV infections. However, oxidant load biomarkers measured before incident infections were not associated, suggesting that the elevation of MDA and anti-HMdU aAb may reflect an ongoing effective immune response, such as increased innate immunity. More research focused on the immune responses to HPV and elevated markers of oxidant load is needed.

Cell-mediated immune response to human papillomavirus 16 E7 peptide pools in patients with cervical neoplasia

OBJECTIVE

To identify characteristics of the cell-mediated immune (CMI) response to human papillomavirus-16 (HPV) E7 viral peptide pools to help the formulation of therapeutic vaccines.

DESIGN

Prospective study. Population. Korean women.

SETTING

University hospital.

METHODS

From December 2008 to August 2010, 33 HPV-16-positive patients, seven patients exhibiting a high-risk HPV infection other than HPV-16 with grade 2/3 cervical intraepithelial neoplasm (CIN2/3), and nine healthy control donors were enrolled.

MAIN OUTCOME MEASURES

CMI response to synthetic HPV-16 E7 overlapping peptide pools using the IFN-γ ELISPOT assay.

RESULTS

The E7 sequence comprising amino acids 16-55 was a major immunogenic region. The CMI response to HPV-16 E7 is highly type-specific. The follow-up CMI response may last longer than expected after the lesion is resected.

CONCLUSIONS

We found that the E7 sequence comprising amino acids 16-55 is a major immunogenic region that is critical for the T-cell-mediated immune response with CIN2/3 or cervical cancer. The identification of CMI responses to HPV-16 E7 peptide pools may provide insight into therapeutic vaccine trials for the control of HPV-associated diseases.

Spinocellular carcinoma from warts in a HPV infection natural history lasting 49 years. Virus strategy or host choice? Implications for researches and therapeutic vaccines

There is a very strong evidence that progression (also to cancer) in variable percentages of cases infected by HPV, HBV, HCV, and HIV depends on host immune response. A large number of observations demonstrate that virus set up a postulated "active strategy" to modify host reactions or to avoid it. But in all those infections it also seems that antigen load (viral RNA or DNA), chronic activation of immune response and time elapsing from the primary infection play a pivotal role in determining clearing or persisting outcomes. My wife's HPV and cancer natural history, lasting 49 years, started at the age of 10 years with facial warts and progressed to CIN 2/3, cervical in situ carcinoma, perineal warts, perianal carcinoma, inguinal lymph nodes, and invasion of bones and muscular structures, until death is paradigmatic: a progressive immune failure was detected in her scaling up all those clinical features, ending in a massive apoptosis of her lymphocytes collected by leukapheresis and cultured with HPV antigens E6/E7, with the aim of obtaining antigen presenting cells and CD8+ specific T lymphocytes. From this experience, a concept of "host choice to reach a tolerance (mainly by a Tregs mediated anergy) or symbiotic-like state" arises, underlining all the affected host's immune-responses to virus persistence (and to consequent tumors). It might be then postulated as the hallmark of a long-term host/parasites co-evolution, and considered a "normal" reaction when the host faces overwhelming numbers of non-self cancer cells (high antigen loads) preceded by persistent virus infections (chronic activation). This happens in patients who do not clear HPV or other viruses soon enough after infection. These observations may lead to a better understanding of many phenomena that are actually difficult to explain or still are open questions. The auto-limiting host's immune-responses are likely to be aimed to avoid risks arising mainly in the protection of "self" (autoimmunity), to prolong its own survival (balance with the virus), to avoid the risk of producing uncontrolled cells (dangerous outcomes). Finally, the postulated negative implications for therapeutic vaccines in cervical cancer, as they really seem to not work till now might be ascribed just to the cited host immune-specific state itself, through an activation induced cell death, elicited by recall antigens (E6/E7 in the case of my wife). Also this latter hypothesis, as well as the previous ones may be of some value to better account for clinical behaviors and researches.

Association between toll-like receptor expression and human papillomavirus type 16 persistence

The mechanisms involved in mucosal immune control of cervical human papillomavirus (HPV) infection remain ill defined. Because toll-like receptors (TLRs) are key players in innate immune responses, we investigated the association between TLR expression and viral persistence or clearance in young women with incident infections with oncogenic HPV types 16 or 51. Messenger RNA expression of TLR1, TLR2, TLR3, TLR4, TLR6, TLR7, TLR8 and TLR9 was measured by quantitative reverse transcription-PCR using human endocervical specimens, collected before and after viral acquisition, in a cohort well characterized for HPV infections. Wilcoxon rank sum test was used to compare the change seen from preinfection to incident infection between women who subsequently cleared infection with those who did not. HPV 16 infections that cleared were significantly (p < 0.05) associated with an increase in expression of the four viral nucleic acid-sensing TLRs (TLR3, TLR7, TLR8 and TLR9) as well as TLR2 upon viral acquisition. Similar associations were not observed for HPV 51. In women who subsequently cleared their HPV 16 infection, changes in TLR1, TLR3, TLR7 and TLR8 expression levels between preincident and incident visits were significantly correlated with parallel changes in the levels of interferon-α2, measured by immunoassay in cervical lavage specimens. This study suggests that dampened TLR expression in the cervical mucosa is a type-specific mechanism by which HPV 16 interferes with innate immune responses, contributing to viral persistence, and that TLR upregulation and resultant cytokine induction is important in subsequent viral clearance.

Human papillomavirus type 16 E6-specific antitumor immunity is induced by oral administration of HPV16 E6-expressing Lactobacillus casei in C57BL/6 mice

Given that local cell-mediated immunity (CMI) against the human papillomavirus type 16 E6 (HPV16 E6) protein is important for eradication of HPV16 E6-expressing cancer cells in the cervical mucosa, the HPV16 E6 protein may be a target for the mucosal immunotherapy of cervical cancer. Here, we expressed the HPV16 E6 antigen on Lactobacillus casei (L. casei) and investigated E6-specific CMI following oral administration of the L. casei-PgsA-E6 to mice. Surface expression of HPV16 E6 antigens was confirmed and mice were orally inoculated with the L. casei-PgsA or the L. casei-PgsA-E6. Compared to the L. casei-PgsA-treated mice, significantly higher levels of serum IgG and mucosal IgA were observed in L. casei-PgsA-E6-immunized mice; these differences were significantly enhanced after boost. Consistent with this, systemic and local CMI were significantly increased after the boost, as shown by increased counts of IFN-γ-secreting cells in splenocytes, mesenteric lymph nodes (MLN), and vaginal samples. Furthermore, in the TC-1 tumor model, animals receiving the orally administered L. casei-PgsA-E6 showed reduced tumor size and increased survival rate versus mice receiving control (L. casei-PgsA) immunization. We also found that L. casei-PgsA-E6-induced antitumor effect was decreased by in vivo depletion of CD4⁺ or CD8⁺ T cells. Collectively, these results indicate that the oral administration of lactobacilli bearing the surface-displayed E6 protein induces T cell-mediated cellular immunity and antitumor effects in mice.

CD4+ T cells against human papillomavirus-18 E7 in patients with high-grade cervical lesions associate with the absence of the virus in the cervix

Cervical neoplastic lesions are associated with infection by high-risk human papilloma-viruses (HPV). The two genotypes most frequently found in the lesions are HPV-16 and HPV-18 with a prevalence of 50-60% and 15-18%, respectively. The E6 and E7 viral oncoproteins are involved in the transformation process and represent foreign antigens for the host. We previously reported that anti-HPV-18 E6 CD4(+) T cells are present in patients with high-grade HPV-18-expressing cervical lesions but also in 50% of the total consecutive patients tested, independently of the HPV type carried. These results indicated that HPV-18 E6 is immunogenic and suggested that all responsive patients, irrespective of the HPV expressed, had encountered HPV-18 and cleared the infection. Here, we investigated anti-HPV-18 E7 CD4(+) T-cell immunity in a cohort of 23 HPV-18 E6-responsive patients. We found that, although E7-specific CD4(+) T cells were present in all women, a robust T helper type (Th1)/Th2 type response against E7 was associated with HPV-18-negative status, suggesting that indeed these patients might have cleared the virus. In agreement with this hypothesis, we found strong anti-E7 CD4(+) T-cell immunity in 20% of 24 healthy donors without evidence of disease. In contrast, a robust Th1/Th2 type response against E6 but not E7 correlated with a lack of disease relapse and/or infection recurrence but did not discriminate between HPV-18-positive and HPV-18-negative patients. Collectively, our data suggest different roles for anti-HPV-18 E6 and E7 CD4(+) T cells in anti-viral and anti-tumour immunity.

An unexpectedly large polyclonal repertoire of HPV-specific T cells is poised for action in patients with cervical cancer

The diversity and extent of the local tumor-specific T-cell response in a given individual is largely unknown. We have performed an in-depth study of the local T-cell repertoire in a selected group of patients with cervical cancer, by systematic analyses of the proportion, breadth, and polarization of human papillomavirus (HPV) E6/E7-specific T cells within the total population of tumor-infiltrating lymphocytes (TIL) and tumor-draining lymph node cells (TDLNC). Isolated T cells were stimulated with sets of overlapping E6 and E7 peptides and analyzed by multiparameter flow cytometry with respect to activation, cytokine production, and T-cell receptor Vbeta usage. HPV-specific CD4+ and CD8+ T-cell responses were detected in TIL and TDLNC and their relative contribution varied between <1% and 66% of all T cells. In general, these HPV-specific responses were surprisingly broad, aimed at multiple E6 and E7 epitopes and involved multiple dominant and subdominant T-cell receptor Vbetas per single peptide-epitope. In most patients, only few IFNgamma-producing T cells were found and the amount of IFNgamma produced was low, suggesting that these are poised T cells, rendered functionally inactive within the tumor environment. Importantly, stimulation of the TIL and TDLNC with cognate antigen in the presence of commonly used Toll-like receptor ligands significantly enhanced the effector T-cell function. In conclusion, our study suggests that within a given patient with HPV-specific immunity many different tumor-specific CD4+ and CD8+ T cells are locally present and poised for action. This vast existing local T-cell population is awaiting proper stimulation and can be exploited for the immunotherapy of cancer.

Human papillomavirus 16-specific T cell responses in classic HPV-related vulvar intra-epithelial neoplasia. Determination of strongly immunogenic regions from E6 and E7 proteins

Cell-mediated immunity directed against human papillomavirus 16 (HPV-16) antigens was studied in 16 patients affected with classic vulvar intra-epithelial neoplasia (VIN), also known as bowenoid papulosis (BP). Ten patients had blood lymphocyte proliferative T cell responses directed against E6/2 (14-34) and/or E6/4 (45-68) peptides, which were identified in the present study as immunodominant among HPV-16 E6 and E7 large peptides. Ex vivo enzyme-linked immunospot-interferon (IFN)-gamma assay was positive in three patients who had proliferative responses. Twelve months later, proliferative T cell responses remained detectable in only six women and the immunodominant antigens remained the E6/2 (14-34) and E6/4 (45-68) peptides. The latter large fragments of peptides contained many epitopes able to bind to at least seven human leucocyte antigen (HLA) class I molecules and were strong binders to seven HLA-DR class II molecules. In order to build a therapeutic anti-HPV-16 vaccine, E6/2 (14-34) and E6/4 (45-68) fragments thus appear to be good candidates to increase HPV-specific effector T lymphocyte responses and clear classic VIN (BP) disease lesions.