This application seeks to evaluate a novel vaccine approach involving targeting the HPV-16 E7 antigen to the MHC class II processing pathway. One of the most important endeavors in evaluating therapeutic vaccines is the measurement of induced in vivo immune responses relevant to anti-tumor efficacy. Recent studies call into question the sensitivity of standard bulk and limiting dilution CTL analyses in estimating the true frequency and functional status of antigen specific T cells. An exciting new approach to directly visualize antigen specific T cells has been the use of multimeric MHC+ peptide complexes that bind stably and specifically to antigen specific T cells. The applicant has developed a simple and versatile approach to MHC-peptide multimerization by linking MHC molecules genetically to a dimeric IgG scaffold. These peptide-MHC-IgG chimeras have been shown to bind stably and specifically to antigen-specific CD8+ and CD4+ T cells. He proposes to utilize these reagents to evaluate the in vivo dynamics and functional status of E7 specific T cells in patients receiving the LAMP targeted E7 vaccines. Specifically, he proposes to: 1) Develop stable CD8+ T cell lines and clones specific for immunodominant HLA-A2 restricted E7 peptides. 2) Develop and test E7-HLA-A2-IgG dimers for three identified immunodominant HLA-A2 restricted E7 peptides. 3) Evaluate the in vivo dynamics of E7+A2 specific CD8+ T cell responses in vaccinated HLA-A2+ patients utilizing the E7-HLA-A2-IgG chimeras developed in Specific Aim 2. 4) Develop analogous E7-MHC II-IgG chimeras capable of detecting CD4+ T cells specific for E7 peptides presented by the common HLA Class II alleles DR1 and DR4. Ultimately, these analyses will test the hypothesis that vaccination of patients expressing HPV 16 E7+ SIL or cervical cancer with LAMP-targeted E7 vaccines increases the numbers of activated E7 specific T cells in peripheral blood and at the site of disease.
