BACKGROUND:Cellular immunity is involved in spontaneous clearance of anogenital warts caused, most typically, by human papillomavirus (HPV) type 6 or 11, supporting the concept of therapeutic vaccination. A therapeutic vaccine composed of HPV-6 L2E7 fusion protein and AS02A adjuvant was evaluated in conjunction with conventional therapies in subjects with anogenital warts.METHODS:A total of 457 subjects with anogenital warts were screened, of which 320 with HPV-6 and/or HPV-11 infection were enrolled into 2 double-blind, placebo-controlled substudies. Three doses of vaccine or placebo were administered along with either ablative therapy or podophyllotoxin.RESULTS:Although a positive trend toward clearance was seen in patients infected with only HPV-6, in neither substudy did the vaccine significantly increase the efficacy of conventional therapies, despite induction of adequate immune responses. Extensive HPV typing by polymerase chain reaction demonstrated that a majority of screened subjects (73.7%) were infected with HPV-6 and/or HPV-11 and that a large proportion (40.1%) were infected with multiple HPV types. HPV types that put subjects at high risk of development of cervical cancer were detected in 39.8% of subjects.CONCLUSIONS:Infection with multiple HPV types, including high-risk types, is common in anogenital wart disease. Therapeutic vaccination failed to increase the efficacy of conventional therapies.

Molecular and ImmunohistochemicaJ analyses ware performed on frozen and paraffin-embedded tissues from a patient with an unusual lymphoproliferative malignancy characterized by the presence of low grade small cleaved cell lymphoma (LGL) In bone marrow (BM), and composite Hodgkin's disease (HD) and high grade small non-cleaved cell lymphoma (HGU within separate areas of a single lymph node (IN). PCR analysis of DMA extracted from each of these three sites revealed evidence of t(14;18) translocation Involving bcl-2 rearrangement at the major breakpoint region (MBR). DNA sequencing of the two separate PCR-ampliflad products from the LN tissue that contained HD and HGL showed evidence of two different donal bcl-2 rearrangements which share MBR breakpoints at the same nudeotide on chromosome 18 and identical N-insertions but which differ by a deletional mutation. This finding is consistent with the presence of two distinct but related donal populations. Reed-Sternberg cells from the HD component of the LN tissue showed reactivity with antibodies directed against CD30 (Ki1), CD 15 (Leu-M1), bcl-2 protein and EBV latent membrane protein (EBVLMP) but not for CD20 (L26). In contrast, the HGL cells stained with antibodies directed against CD20 and bcl-2 protein and not with CD30, CD 15 or EBV-LMP, findings shared with the LGL cells in BM, and did not exhibit EBV or HD markers. Additionally, p53 expression was detected in the HD and HGL tissues but not in the LGL cells. Our findings suggest that 1) the composite HD and HGL originated from a single clone and 2) the acquisition of EBV infection and p53 expression are associated with the development of HD in this patient. ANALYSIS OF MHC CLASS I EXPRESSION ON REED-STERNBERG CELLS IN RELATION TO THE CYTOTOXIC T-CELL RESPONSE IN EPSTEIN-BARR VIRUS POSITIVE AND NEGATIVE HODGKIN'S DISEASE JJ Oudejans, NM Jiwa, JA Kummer, A Horstman, W Vos, JPA Bank, PhM Kluin*. P van der Valk, JMM Walboomers and CJLM Meijer Depts of Pathology, Free University Hospital Amsterdam and University Hospital Leiden*, The Netherlands

AIMSNo good predictive marker for the malignant transformation of potentially malignant oral lesions (PMOLs) is currently available. This study re-evaluated the value of p53 immunoexpression to predict malignant transformation of PMOLs after discounting possible confounding factors.METHODSPMOLs from 18 patients who showed progression to carcinoma, 16 of the respective carcinomas, and PMOLs from 18 matched controls were evaluated by immunohistochemistry (IHC) for p53 expression. A mouse monoclonal antibody that detects wild-type and mutant forms of human p53 was used. The p53 immunostaining pattern was also correlated with the degree of dysplasia.RESULTSSuprabasal p53 staining was significantly associated with high grades of dysplasia (p < 0.01). The specificity and positive predictive value (PPV) for malignant transformation of suprabasal p53 staining were superior to the assessment of dysplasia, but sensitivity was inferior. All carcinomas derived from PMOLs with suprabasal p53 showed strong p53 immunostaining. However, the absence of suprabasal p53 staining and/or dysplastic changes did not preclude malignant transformation in a considerable proportion of PMOLs.CONCLUSIONSThis study confirms and extends previous findings that suprabasal p53 immunoexpression has a high PPV for malignant transformation of PMOLs and can be used as a specific marker for lesions that are at high risk for malignant transformation. The absence of suprabasal p53 staining (that is, absence of, or basal, p53 staining) is non-informative for prognostic purposes. Because of its limited sensitivity, p53 IHC is not a substitute for the assessment of dysplasia in the evaluation of PMOLs. Instead, p53 IHC emerges as a clinically useful supplement of histopathological assessment in the prognosis of PMOLs.

OBJECTIVE: To investigate the rate of clearance of human papillomavirus (HPV) infection after surgical treatment for cervical intraepithelial neoplasia (CIN).METHODS: One hundred nine women with CIN I-III, treated with cryosurgery or conization at a university hospital, were observed with cervical HPV deoxyribonucleic acid (DNA) testing by general primer polymerase chain reaction and HPV typing at 0, 3, 6, 9, 12, and 24 months after treatment. Penile HPV DNA was analyzed from current sexual partners.RESULTS: Eighty-one percent of evaluable women were HPV DNA positive at treatment or enrollment. One year later, seven women (9%) remained positive for the same HPV type. Most women had cleared the HPV infection diagnosed at treatment within 3 months. The cryotherapy group had lower CIN grades, was younger, and had a slower HPV clearance rate (P < .002). Only four couples had HPV DNA of the same type detected.CONCLUSION: Surgical treatment of CIN usually results in clearance of HPV infection within 3 months. Human papillomavirus DNA testing may be useful as a rapid intermediate end point for monitoring the efficacy of treatments.

BACKGROUND:High-risk human papillomavirus (HPV) types play a major role in the development of cervical cancer in vivo and can induce immortalization of primary human keratinocytes in vitro. Activation of the telomere-lengthening enzyme telomerase constitutes a key event in both processes. Because losses of alleles from chromosome 6 and increased telomerase activity have been observed in high-grade premalignant cervical lesions, we analyzed whether human chromosome 6 harbors a putative telomerase repressor locus that may be involved in HPV-mediated immortalization.METHODS:Microcell-mediated chromosome transfer was used to introduce chromosomes 6 and 11 to the in vitro generated HPV type 16 (HPV16)-immortalized keratinocyte cell line FK16A and to the in vivo derived HPV16-containing cervical cancer cell line SIHA: Hybrid clones were analyzed for growth characteristics, telomerase activity, human telomerase reverse transcriptase (hTERT) and HPV16 E6 expression, and telomere length. FK16A hybrid clones were also transduced with an hTERT-containing retrovirus to examine the effect of ectopic hTERT expression on growth. Statistical tests were two-sided.RESULTS:Introduction of human chromosome 6 but not of chromosome 11 to both cell lines yielded hybrid cells that demonstrated crisis-like features (i.e., enlarged and flattened morphology, vacuolation, and multinucleation) and underwent growth arrest after a marked lag period. In the chromosome 6 hybrid clones analyzed, telomerase activity and hTERT messenger RNA (mRNA) expression were statistically significantly reduced compared with those in the chromosome 11 hybrid clones (for telomerase activity, P =.004 for the FK16A hybrids and P =.039 for the SiHa hybrids; for hTERT mRNA expression, P =.003 for the FK16A hybrids). The observed growth arrest was associated with telomeric shortening. Ectopic expression of hTERT in FK16A cells could prevent the telomeric shortening-based growth arrest induced by chromosome 6.CONCLUSIONS:Chromosome 6 may harbor a repressor of hTERT transcription, the loss of which may be involved in HPV-mediated immortalization.

BACKGROUND/AIMS:To improve the accuracy of conventional cytology in cervical cancer screening, high risk human papillomavirus (HPV) testing and neural network based screening have been developed. This study assessed the power of both techniques to detect women at risk of developing incident CIN III; that is, CIN III detected during the follow up of women with normal cytology and borderline nuclear changes.METHODS:A cohort of 2250 women, 34-54 years of age, who attended population based cervical cancer screening from 1988 to 1991 and had normal smears or borderline nuclear changes was followed. All smears were tested for high risk HPV and the smears were rescreened using neural network based screening. The value of neural network based screening for predicting incident CIN III during a mean follow up period of 6.4 years was compared with that of high risk HPV testing. In addition, morphological markers presumed to be related to HPV were correlated with HPV status.RESULTS:Thirteen (0.6%) women had incident CIN III. Both high risk HPV positivity and abnormal cytology were associated with an increased risk for incident CIN III (odds ratio, 240 and 22, respectively) and high risk HPV positivity was associated with abnormal cytology. The sensitivity of high risk HPV testing for predicting incident CIN III was much higher than that of neural network based screening (92% and 46%, respectively). None of the morphological markers assessed, including koilocytosis, was correlated with high risk HPV status.CONCLUSION:High risk HPV testing is superior to neural network based screening in identifying women at risk of developing CIN III. For women with normal cytology and borderline changes and a negative high risk HPV test, the screening interval can be considerably prolonged.

HPV types 16 and 18 have been categorized as human carcinogens based on their strong associations with cervical cancer in previous case-control studies. Recent IARC studies in the Philippines, Thailand and Morocco show strong associations between invasive cervical cancer and less common HPV types, including HPV 31, 33, 45, 51, 52 and 58. We present results of a further IARC case-control study conducted in Asunción, Paraguay, to examine the association between specific HPV types and invasive cervical cancer as well as risk factors other than HPV. One-hundred thirteen incident histologically confirmed invasive cervical cancer cases and 91 age-matched hospital controls were recruited. A standardized questionnaire was administered to investigate known and suspected risk factors for cervical cancer. For HPV status determination, cervical biopsy specimens from case subjects and exfoliated cervical cells from control subjects were obtained. HPV DNA was ascertained using a GP5+/6+ PCR-based assay capable of detecting more than 33 HPV types. Overall HPV prevalence was 97% in the cervical cancer cases and 20% in the control subjects. As a single infection, HPV 16 was the predominant type with a prevalence of 48% among case subjects and 5.5% among control subjects. Significant associations with the risk of cervical cancer were detected as follows: any HPV type (OR = 114; 95% CI: 36-361); HPV 16 (OR = 910); HPV 18 (infinite OR); HPV 31 (OR = 110); HPV 33 (OR = 261); HPV 45 (OR = 129); and HPV 58 (OR = 36). In the multivariate model, risk factors other than HPV significantly associated with cervical cancer risk were a higher number of lifetime sexual partners, lower educational status and never having had a Pap smear. Strong associations were found between invasive cervical cancer and specific HPV types 16, 18, 31, 33, 45 and 58.

Reports on the association of EBV with oral squamous-cell carcinomas (OSCCs) are scarce and inconclusive. To determine the potential role of EBV in oral carcinogenesis, we investigated 36 EBV DNA PCR-positive OSCCs for the expression of EBV transcripts and proteins. From these EBV DNA-positive OSCCs, 13 were analysed for the presence of EBV products, either at RNA and/or protein level. EBER transcripts were investigated by RNA in situ hybridisation. EBNA-1, EBNA-2, LMP-1, LMP-2, BHRF1 and BARF0 transcripts were investigated by RT-PCR and/or NASBA. EBNA-1, LMP-1 and ZEBRA protein expressions were investigated by immunohistochemistry. All 36 OSCCs were positive for EBV DNA, using the highly sensitive BamHI W PCR, and 18 of these (50%) were positive using the less-sensitive PCR, which targets BNLF-1. However, virtually all OSCCs tested failed to reveal EBV transcripts, including EBERs and EBNA-1 transcripts. No ZEBRA and LMP-1 proteins were found in the neoplastic or any other cells of the OSCCs investigated. Immunohistochemistry using a monoclonal antibody (MAb) raised against EBNA-1 (2B4) resulted in positive staining in some cases of OSCCs, but these results were non-specific, since EBV-negative epithelial tissues showed extensive non-specific staining and no EBNA-1-specific transcripts were detected by RT-PCR or NASBA. The absence of expression of EBV encoded transcripts and proteins indicate that, with the present knowledge on EBV, an active role in oral carcinogenesis for this virus is unlikely.

Infection with oncogenic human papillomavirus (HPV) types is associated with the development of cervical neoplasia (CIN). The E6 and E7 oncoproteins are constitutively expressed in these lesions and are therefore putative targets for the immune response against HPV. The relation between HPV 16-specific memory cytotoxic T-cell precursor (mCTLp) activity to both oncoproteins and the natural course of cervical dysplasia was analyzed in 38 patients participating in a nonintervention cohort study of women with CIN and 11 HPV 16-positive cervical carcinoma patients. In a cross-sectional study at the end of follow-up prior to biopsy, 8 of 20 patients with a persistent HPV 16 infection had specific mCTLp against at least one of the two oncoproteins. By contrast, no specific mCTLp activity was detected in 11 HPV-negative patients or in 7 patients who had cleared an HPV 16 infection at the end of follow-up. However, 5 of 11 cervical carcinoma patients showed mCTLp activity against the E7 protein only. This study demonstrates that HPV 16 oncogene-specific mCTLp are present in women with HPV 16-positive CIN prior to any intervention. Since HPV-specific mCTLp were detected predominantly in women with high-grade lesions or invasive cervical carcinoma and not in women who cleared the virus, the role of naturally occurring mCTLp in the protection against HPV-associated cervical neoplasia remains to be established.

p53 is a tumour suppressor gene encoding a protein whose function is impaired in a very large proportion of human cancers. The objectives of this study were to determine the natural history of p53 alterations during stages of oral carcinogenesis, by comparing p53 immunoexpression in oral squamous cell carcinomas (OSCCs), their non-malignant adjacent mucosa, and respective metastases; and to define the potential practical consequences for clinical management of p53 staining in the non-malignant adjacent mucosa. Forty-two samples of non-malignant mucosa adjacent to OSCCs, the respective carcinomas, and six lymph node metastases derived from six of the OSCCs were investigated for p53 protein expression by immunohistochemistry. Seven out of 42 (17%) non-malignant mucosal samples immediately adjacent to OSCC showed suprabasal p53 staining and this was significantly associated with moderate/severe dysplasia (p=0.02). In six of these cases (86%), the respective carcinoma showed p53 immunoexpression in more than 50% of the neoplastic cells and in the remaining case, p53 immunoexpression was found in more than 25% of the neoplastic cells. In all p53-negative carcinomas that showed p53 immunoexpression in the non-malignant adjacent mucosa, p53 staining was never detected above the basal cell layer. Lymph node metastases showed the same patterns of p53 immunoexpression as the carcinomas from which they were derived. When suprabasal p53 staining is present in non-malignant mucosa immediately adjacent to OSCCs, this suggests stable p53 alterations which are maintained upon progression to overt malignancy. The immunostaining in non-malignant mucosa of the resection margins of OSCCs might be a valuable predictor for local recurrences and may therefore have implications for the management of patients who have received surgical treatment for OSCC.

Replicative senescence of T cells is correlated with erosion of telomere ends. Telomerase plays a key role in maintaining telomere length. Therefore, it is thought that telomerase regulates the life span of T cells. To test this hypothesis, we have over-expressed human telomerase reverse transcriptase in human CD8(+) T cells. Ectopic expression of human telomerase reverse transcriptase led to immortalization of these T cells, without altering the phenotype and without loss of specificity or functionality. As the T cells remained dependent on cytokines and Ag stimulation for their in vitro expansion, we conclude that immortalization was achieved without malignant transformation.

Before guidelines can be set for the use of high-risk human papillomavirus (HR HPV) testing in cervical cancer screening and vaccine preparation, age-related prevalence of HR HPV types in cytologically normal smears has to be known. Therefore, in a cross-sectional study the prevalence of 37 different HPV genotypes and putatively unidentified HPV types was determined in 3,305 cytologically normal cervical smears from the general female population (15–69 years of age) using an HPV general primer GP5+/bioGP6+ mediated PCR assay. Subsequently, HPV-positive cervical smears were typed for 19 HR and 18 low-risk (LR) HPVs with an enzyme immunoassay using HPV type-specific oligoprobes in cocktails and individually, respectively. Overall, −HR and −LR HPV prevalences appeared to be of 4.6%, 3.3%, and 1.0%, respectively. Twenty-six different HPV types were detected in the 152 HPV-positive samples, the most prevalent types being HPV 16, 31, and 18. With regard to age, a peak prevalence of 19.6% for all HPVs was found in women 25–29 years of age, which declined to a mean of 4.3% in women over 30 years. With regard cytologically normal cervical smears (n = 3,011) of women participating in the population-based screening program in the Netherlands (30 to 60 years), all HR HPVs showed decreased occurrence with increasing age, whereas the prevalence of LR HPV types remained constant. We suggest that screening for abnormal cytology implies screening for HR HPV infections and the subsequent treatment results in a decline of HR HPV prevalence in contrast to LR HPV prevalence during the years of screening. Int. J. Cancer 87:221–227, 2000. © 2000 Wiley-Liss, Inc.

Background A relation has been established between infection with high-risk types of human papillomavirus and development of cervical cancer. We investigated a role for testing for human papillomavirus as part of cervical-cancer screening.Methods We monitored by cytology, colposcopy, and testing for high-risk human papillomavirus 353 women referred to gynaecologists with mild to moderate and severe dyskaryosis. The median follow-up time was 33 months. At the last visit we took biopsy samples. Our primary endpoint was clinical progression, defined as cervical intraepithelial neoplasia (CIN) 3, covering three or more cervical quadrants on colposcopy, or a cervical-smear result of suspected cervical cancer.Findings 33 women reached clinical progression. All had persistent infection with high-risk human papillomavirus. The cumulative 6-year incidence of clinical progression among these women was 40% (95% CI 21-59). in women with end histology CIN 3, 98 (95%) of 103 had persistent infection with high-risk human papillomavirus from baseline. Among women with mild to moderate dyskaryosis at baseline, a second test for human papillomavirus at 6 months predicted end histology CIN 3 better than a second cervical smear.Interpretation Persistent infection with high-risk human papillomavirus is necessary for development and maintenance of CIN 3. All women with severe dyskaryosis should be referred to gynaecologists, whereas women with mild to moderate dyskaryosis should be referred only after a second positive test for high-risk human papillomavirus at 6 months.

A recent report that 93 per cent of invasive cervical cancers worldwide contain human papillomavirus (HPV) may be an underestimate, due to sample inadequacy or integration events affecting the HPV L1 gene, which is the target of the polymerase chain reaction (PCR)‐based test which was used. The formerly HPV‐negative cases from this study have therefore been reanalysed for HPV serum antibodies and HPV DNA. Serology for HPV 16 VLPs, E6, and E7 antibodies was performed on 49 of the 66 cases which were HPV‐negative and a sample of 48 of the 866 cases which were HPV‐positive in the original study. Moreover, 55 of the 66 formerly HPV‐negative biopsies were also reanalysed by a sandwich procedure in which the outer sections in a series of sections are used for histological review, while the inner sections are assayed by three different HPV PCR assays targeting different open reading frames (ORFs). No significant difference was found in serology for HPV 16 proteins between the cases that were originally HPV PCR‐negative and ‐positive. Type‐specific E7 PCR for 14 high‐risk HPV types detected HPV DNA in 38 (69 per cent) of the 55 originally HPV‐negative and amplifiable specimens. The HPV types detected were 16, 18, 31, 33, 39, 45, 52, and 58. Two (4 per cent) additional cases were only HPV DNA‐positive by E1 and/or L1 consensus PCR. Histological analysis of the 55 specimens revealed that 21 were qualitatively inadequate. Only two of the 34 adequate samples were HPV‐negative on all PCR tests, as against 13 of the 21 that were inadequate ( p< 0·001). Combining the data from this and the previous study and excluding inadequate specimens, the worldwide HPV prevalence in cervical carcinomas is 99·7 per cent. The presence of HPV in virtually all cervical cancers implies the highest worldwide attributable fraction so far reported for a specific cause of any major human cancer. The extreme rarity of HPV‐negative cancers reinforces the rationale for HPV testing in addition to, or even instead of, cervical cytology in routine cervical screening. Copyright © 1999 John Wiley & Sons, Ltd.

Serum samples from 194 cases and 217 controls participating in a case-control study of invasive cervical cancer in Brazil were examined for antibodies to human papillomavirus (HPV) 16 virus-like particles (VLPs) by ELISA. The prevalence of antibody in cases and controls was 47.4 versus 24.4% (P < 0.001). The prevalence was higher in women who had HPV-16 DNA in the genital tract (54.2%) than in those with other HPVs (36.8%) or no HPVs (44.8%), but the differences were not statistically significant. Among cases and controls, HPV-16 VLP antibodies were associated with a greater number of lifetime sexual partners (chi2 for trend, P < 0.001). Among controls, age was inversely associated with HPV-16 VLP seroreactivity (chi2 for trend, P = 0.019). The sera were previously tested for antibodies to HPV-16 E6 and E7 oncoproteins; there was no correlation between antibody titers to HPV-16 E6 or E7 and VLPs. The HPV-16 serological assays were compared as screening tests for invasive cervical cancer. The sensitivity and specificity estimates were 47.4 and 75.6% for HPV-16 VLP serology, 63.4 and 89.9% for either HPV-16 E6 or E7 serology, and 53.6 and 93.6% for high titers of either HPV-16 E6 or E7 or VLP antibodies. The utility of HPV-16 VLP ELISA as a screening test for invasive cervical cancer is limited by a high seroprevalence in women with probable prior exposure to HVP 16 but without disease.

T-cell-mediated immune responses against mucosal oncogenic types of human papillomaviruses (HPV) are thought to play a role in the control of the virus infection and its associated cervical lesions. The in vitro production of interleukin-2 by T-helper (Th) cells in response to the C-terminal and N-terminal domains of the HPV-16 E2 protein was determined in 74 women with cytological evidence of premalignant cervical epithelial neoplasia who participated in a non-intervention follow-up (FU) study. Cross-sectional analysis at the end of FU showed that Th cell responses against the C-terminal domain were associated with evidence of previous or present HPV-16 infection as compared to patients with no evidence of any HPV infection (18.9% versus 0%, P = 0.039). Th cell responses against the N-terminal domain were not associated with evidence of HPV-16 infection. No association with disease outcome was observed with Th cell responses against either of the E2 protein domains. However, longitudinal analysis revealed that Th cell responses against the C-terminal domain frequently occur at the time of virus clearance. Whether these responses are responsible for the clearance of the virus is not known.

BACKGROUND: The development of a reproducible, sensitive, and standardised human papillomavirus (HPV) polymerase chain reaction (PCR) test is required to implement HPV testing in cervical cancer screening programmes and for triaging women with mild to moderate dysplasia. AIMS: To determine the intermethod agreement between different GP5+/6+ and MY09/11 PCR based protocols for the detection and typing of high risk (HR) HPV DNA in cervical smears and to assess the intramethod reproducibility of the GP5+/6+ PCR enzyme immunoassay (EIA) for HR-HPV detection. METHODS: For the intermethod comparison, crude aliquots of 20 well characterised cervical smears comprising five HPV negative samples, and six and nine samples containing single and multiple HPV infections, respectively, were coded and sent from reference laboratory (A) to three other laboratories. One of these (laboratory B) used the GP5+/6+ PCR-EIA and was provided with standard protocols. Another laboratory (C) used GP5+/6+ PCR combined with sequence analysis and type specific PCR, whereas two laboratories (D and E) used MY09/11 PCR followed by restriction fragment length polymorphism (RFLP) analysis for the detection and typing of HR-HPV. The intramethod agreement of GP5+/6+ PCR-EIA was analysed in a subsequent study with four other laboratories (F to I) on crude aliquots of 50 well characterised cervical smears, consisting of 32 HR-HPV positive and 18 HPV negative samples. Standardised protocols, primers, and probes were also provided by the reference laboratory for HR-HPV detection. RESULTS: In the intermethod comparison, pairwise agreement of the different laboratories with reference laboratory A for the detection of HR-HPV varied between 75% and 100% (kappa values: 0.5 to 1). Typing data revealed a broader range in pairwise agreement rates between 32% and 100%. The highest agreement was found between laboratories A and B using standardised protocols and validated reagents. In the intramethod evaluation, pairwise comparison of the laboratories F to I with reference laboratory A revealed excellent agreement rates from 92% to 100% (kappa values: 0.88 to 1.0) with an overall sensitivity of 97.5% (195/200) and specificity of 99.5% (199/200). CONCLUSIONS: The detection of HR-HPV as a group is highly reproducible with GP5+/6+ PCR-EIA provided that standardised protocols and validated reagents are used.

T-helper (Th) cell-dependent IL-2 production and plasma IgG responses to virus-like particles consisting of the human papillomavirus type 16 (HPV-16) major capsid protein L1 (L1-VLP) were determined in patients with cytological evidence of cervical intraepithelial neoplasia (CIN) participating in a non-intervention prospective cohort study. IgG responses were associated with HPV-16 persistence and high-grade CIN lesions, while high frequencies of Th responses were observed in patients with both virus clearance and virus persistence, irrespective of CIN grade. The IgG response was found in conjunction with an IL-2 response to L1-VLP in 87% of the patients. Recognition of the HPV-16 L1 Th epitope (amino acids 311-335) was found to be more closely associated than recognition of L1-VLP as a whole to HPV exposure and CIN development. Among the HPV-16+ patients included in this study, those showing a Th response to amino acids 311-335 were more likely to carry the HLA DRB1*11/DQB1*0301 haplotype, while those showing an IgG response to L1-VLP were more likely to carry DRB1*0101/DQB1*0501. However, neither cell-mediated nor humoral immune responses against HPV-16 L1 appear to be sufficient for the natural control of HPV infection and CIN development.