ROLE OF TNF FAMILY MEMBERS IN MEMORY B CELL DEVELOPMENT

近年来，调控幼稚B细胞向记忆B细胞室分化的因素引起了人们的广泛关注。不幸的是，记忆B细胞发育的研究一直很困难，因为这些B细胞的频率非常低。我们已经开发了一个体内模型系统，其中B细胞分化事件发生的频率很高，因此可以对建立记忆所涉及的必要因素进行深入的评估。该系统的新特点包括利用Ig转基因B细胞(称为QM B细胞)，这种B细胞是抗原特异性的，具有同型转换和体细胞突变的能力。有待检验的基本假设是，肿瘤坏死因子家族成员(TNFpha、LTalpha、OX40L、CD40L)对记忆B细胞的生成和维持起着不同的调节作用。特异性的目的有两个：1)鉴定T细胞依赖抗原诱导的QM B细胞分化为记忆性B细胞；2)使用肿瘤坏死因子家族成员的阻断试剂来评估QM B细胞分化受阻的阶段(S)。这些将通过进行过继转移实验来实现，表型分析将通过流式细胞仪和多色共聚焦成像进行评估。QM B细胞向记忆B细胞池的分化将通过二次转移实验和QM B细胞产生高亲和力、同型转换、体细胞突变抗体的能力来检测。这些研究将阐明与记忆B细胞分化有关的因素，并有助于疫苗的开发以及自身免疫性疾病的免疫治疗。

In recent years, considerable attention has been focused on the factors involved in regulating the differentiation of naive B cells to the memory B cell compartment. Unfortunately, the study of memory B cell development has been difficult due to the extremely low frequency of these B cells. We have developed an in vivo model system in which the events of B cell differentiation occur at a high frequency, and thus will allow for the incisive evaluation of the requisite factors involved in establishing memory. The novel features of this system include the utilization of Ig transgenic B cells (referred to as QM B cells) which are antigen-specific, and have the ability to isotype switch and undergo somatic mutation. The underlying hypothesis to be tested is that TNF family members (TNFalpha, LTalpha, OX40L, CD40L) differentially regulate the generation and maintenance of memory B cells. The specific aims are two-fold: 1) to characterize QM B cells induced to differentiate into memory B cells in response to a T cell-dependent antigen, and 2) use blocking reagents to TNF family members to assess the stage(s) in which QM B cell differentiation is disrupted. These will be achieved by performing adoptive transfer experiments and phenotypic analysis will be assessed by flow cytometry and multi-color confocal imaging. QM B cell differentiation into the memory B cell pool will be examined by secondary transfer experiments and the capacity of QM B cells to generate high affinity, isotype switched, somatically mutated antibodies. These studies will elucidate factors involved in memory B cell differentiation, and contribute to vaccine development as well as immunotherapy for autoimmune disease.