The applicants propose to continue an ongoing prospective study in which women with CIN I or II are recruited and followed in order to identify biomarkers associated with regression of CIN. The following factors will be assessed: (1) humoral immune response to virus-like particles (VLPs) of HPV types 6, 16, 18, 31, 53, and 58, (2) cell-mediated immunity (CMI) to HPV 16 E6 and E7 peptides, (3) class II HLA DQB1 and DRB1 alleles, (4) plasma ascorbic acid level, and (5) red blood cell (RBC) folate level. Continuation of this existing study is necessary to increase sample size and thus provide sufficient statistical power to better understand how these host factors may interact to influence the outcome of CIN. Women will be recruited from the colposcopy clinics of 3 hospitals associated with the Albert Einstein College of Medicine and followed at 3-month intervals by Pap smear and colposcopy for 12 months. At this point, an endpoint biopsy will be performed to determine whether CIN lesions are present ('persistence') or absent ('regression'). At each visit, cervico-vaginal lavage specimens will be collected for HPV DNA analyses by Southern blot and polymerase chain reaction (PCR). Blood will be collected for HPV VLP serology, T cell proliferative response (CMI) assay, plasma reduced ascorbic acid by high pressure liquid chromatography, and RBC folate levels by immunoassay. DNA typing of class II HLA alleles by PCR will be performed using blood collected at baseline. Associations between these factors and regression of CIN will be assessed by appropriate univariate and multivariate analyses.