Frequency and phenotype of Fel d 1-specific T cells after peptide therapy

项目总结（见说明）： 这项研究计划的广泛，长期目标是了解肽免疫疗法，使用主要过敏原（Fel d 1）的验证T细胞表位，调节Fel d 1特异性T细胞的频率和功能表型，使用独特的MHC II类四聚体试剂。 我们假设肽免疫疗法导致在肽免疫疗法后过敏原特异性T细胞的频率和功能表型的调节。 具体目标1将确定肽免疫疗法（PIT）对患有严重程度增加的猫过敏性哮喘的受试者中的Fel d 1特异性（四聚体+）T细胞的影响。从猫过敏性哮喘受试者（按严重程度分层的组）中肽免疫疗法的II期临床试验中收集的冷冻外周血单核细胞（PBMC）档案将用于确定过敏原特异性（MHC II类四聚体+）T细胞的频率和功能表型。 具体目标2将采用肽免疫治疗猫过敏性鼻炎的前瞻性临床试验。将在基线、治疗结束后不久（第18-22周）和研究开始后一年抽取大量血液（200 ml）。四聚体+ T细胞将使用顺序磁性纯化来富集 确定肽免疫疗法是否改变变应原特异性四聚体+ T细胞中的频率、记忆表型、趋化因子受体表达和调节性T细胞功能的标志物。 具体目标3将阐述疫苗肽对MHC的亲和力如何影响肽的临床功效（其诱导免疫耐受性的能力）。由于表达的MHC分子的复杂性以及每种肽与多个MHC分子结合，本研究无法在人类受试者中进行。 因此，本研究将在表达人MHC基因HLA-DR 4的小鼠中进行。构成目的1和2中使用的肽疫苗的7种肽对HLA-DR 4具有不同的亲和力。将对每种肽进行评估，以确定功效与亲和力的关系。

PROJECT SUMMARY (See instructions): The broad, long term objective of this research proposal is to understand how peptide immunotherapy, using validated T cell epitopes of a major allergen (Fel d 1), modulates the frequency and functional phenotype of Fel d 1-specific T cells, using unique MHC Class II tetramer reagents. We hypothesize that peptide immunotherapy results in modulation of the frequency and functional phenotype of allergen-specific T cells following peptide immunotherapy. Specific Aim 1 will determine the effects of peptide immunotherapy (PIT) on Fel d 1-specific (tetramer+) T cells in subjects with cat allergic asthma of increasing severity. An archive of frozen peripheral blood mononuclear cells (PBMC) collected from a Phase II clinical trial of peptide immunotherapy in subjects with cat allergic asthma (groups stratified for severity) will be used to determine the frequency and functional phenotype of allergen-specific (MHC class II tetramer+) T cells. Specific Aim 2 will employ a prospective clinical trial of peptide immunotherapy in cat allergic rhinitis. Large volumes (200ml) of blood will be drawn at baseline, shortly after the end of treatment (week 18-22) and one year after the initiation of the study. Tetramer+ T cells will be enriched using sequential magnetic purification to determine whether peptide immunotherapy changes frequency, memory phenotype, chemokine receptor expression and markers of regulatory T cell function among allergen-specific tetramer+ T cells. Specific Aim 3 will address how the affinity of vaccine peptides for the MHC affects the clinical efficacy of the peptide (its ability to induce immunological tolerance). This study cannot be performed in human subject due to the complexity of MHC molecules expressed and because each peptide binds to multiple MHC molecules. Therefore the study will be conducted in mice that express the human MHC gene, HLA-DR4. The 7 peptides comprising the peptide vaccine employed in Aims 1 & 2 have differing affinity for HLA-DR4. Each peptide will be evaluated to determine how efficacy relates to affinity.