Augmentation of Anti-Tumor Activity in the Absence of B Cells

强生； 细胞溶解T细胞(CTL)和Th1应答是抗肿瘤免疫的重要效应机制。小才是 已知B细胞在调节抗肿瘤反应中的作用。IgM“‘”B细胞缺陷小鼠(BCDM) 与免疫活性小鼠(ICM)相比，对原发肿瘤的抵抗力增强。三个同源基因中的两个 在BCDM中，肿瘤(EL4和MC38)自发消退，而第三种肿瘤(B16)的生长明显放缓。 BCDM的抗肿瘤耐药性增强与T细胞浸润增加、Th1增强有关 细胞因子应答和CTL活性升高。野生型而非OX40L“7”B的BCDM重组 细胞导致肿瘤抵抗力降低。B细胞的缺失可能导致Th1和CTL的增强 对肿瘤的反应。 这项提案的总体目标是了解导致增强抗肿瘤作用的机制。 在没有B细胞的情况下做出反应，并确定B细胞是否主动耗尽 正常主机将复制导致增强响应的条件。 在AIM/我们将研究ICM和BCDM中看到的抗肿瘤T细胞反应，并描绘T细胞 淋巴亚群耗尽和/或过继增强肿瘤耐药性的反应 传递实验。还将研究CD4+CD25+T调节细胞的潜在作用。在AIM II中， 我们将研究B细胞抑制抗肿瘤免疫的免疫调节机制。 我们将研究野生型和OX40L“‘”B细胞重组对扩增和分化的影响 BCDM中肿瘤特异性CD4+和CD8+T细胞与抗肿瘤反应的关系我们将确定B细胞效应器 可能在抑制抗肿瘤反应中发挥作用的亚群。我们将确定是否会有其他 候选B细胞衍生因子或受体，如CD40、IL-10和转化生长因子-3，可能在抑制抗- 肿瘤免疫。我们将检查BCDM中的抗原提呈细胞(树突状细胞)是否发生了变化 可能导致肿瘤免疫力增强的特性。在AIM III中，我们将开发亲-亲本的小鼠模型 活化B细胞耗竭及研究B细胞耗尽对抗肿瘤免疫应答的影响 与其他免疫干预策略相结合，例如细胞因子传递、基因转移和/或 领养T细胞转移。利妥昔单抗和其他药物对B细胞耗尽的影响将在 人CD20-BAC转基因小鼠，模拟CD20在B细胞中的正常表达模式。我们会 检测huCD20-BAC转基因骨髓移植后B细胞的直接耗竭或耗竭 受辐射的宿主小鼠。由于使用单抗可以有效且安全地耗尽人体内B细胞 例如利妥昔单抗，在AIM III中开发的策略可以很容易地应用于L/11期人体试验的设计。

j < Cytolytic T cell (CTL) and Th1 responses are important effector mechanisms in anti-tumor immunity. Little is known about role of B cells in regulating anti-tumor responses. IgM"'" B cell-deficient mice (BCDM) exhibit enhanced resistance to primary tumors compared to immunocompetent mice (ICM). Two of three syngeneic tumors (EL4 and MC38) regress spontaneously in BCDM while growth of a third (B16) was markedly slowed. Enhanced anti-tumor resistance of BCDM was associated with increased T cell infiltration, enhanced Th1 cytokine response and increased CTL activity. Reconstitution of BCDM with wild type but not OX40L"7"B cells results in decreased tumor resistance. The absence of B cells may result in enhanced Th1 and CTL responses to tumors. The overall goal of this proposal is to understand mechanisms leading to an enhanced anti-tumor response in the absence of B cells, and determine whether the proactive depletion of B cells in normal hosts will replicate conditions leading to an enhanced response. In Aim /we will study the anti-tumor T cell responses seen in ICM and BCDM and delineate the T-cell responses involved in augmentation of tumor resistance by depletion of lymphoid subsets and/or adoptive transfer experiments. The potential role of CD4+ CD25+ T regulatory cells will also be investigated. In Aim II, we will examine the immunoregulatory mechanisms underlying inhibition of anti-tumor immunity by B cells. We will study the effects of reconstitution with wild type and OX40L"'" B cells on expansion and differentiation of tumor specific CD4+ and CD8+ T cells and anti-tumor response in BCDM. We will identify B cell effector subsets that may play a role in inhibiting anti-tumor responses. We will determine whether additional candidate B cell-derived factors or receptors such CD40, IL-10, and TGF-3 may play a role in inhibiting anti- tumor immunity. We will examine whether antigen presenting cells (dendritic cells) in BCDM have altered properties that may lead to the enhanced tumor immunity. In Aim III, we will develop murine models for pro- active B cell depletion and study the effect of B cell depletion on anti-tumor immune responses, alone or in combination with other immune intervention strategies such as cytokine delivery, gene transfer, and/or adoptive T cell transfer. Effects of B cell depletion using Rituximab and additional agents will be modeled in a human CD20-BAC transgenic mouse which mimics normal patterns of CD20 expression in B cells. We will test direct B cell depletion or depletion following transplant of huCD20-BAC transgenic bone marrow into irradiated host mice. Since B cells can be efficiently and safely depleted in man using monoclonal antibodies such asRituximab, strategies developed in Aim III canreadily be applied to design of human Phase l/ll trials.