Antibody V Gene Expression B Cell Lymphocytic Leukemia

我们在确定免疫球蛋白（Ig）可变区基因（V基因）在慢性淋巴细胞白血病（CLL）中的应用方面取得了重大进展。先前的研究表明，对Ig V基因库的限制已经扩展，揭示在CLL中表达的Ig可能是因为它们能够结合多种低亲和力的自身抗原而被选择的。我们用表达这种多反应性人IgM的B细胞转基因小鼠，发现这些细胞可以分化为边缘区（MZ）记忆型B细胞。这种mzb细胞与CLL细胞具有相同的基因表达谱。这些和其他新开发的CLL转基因小鼠模型将使我们能够评估Ig受体信号是否在白血病发生和/或疾病进展中发挥作用。最近的研究表明，与表达未突变Ig基因的CLL细胞相比，表达突变Ig基因的CLL细胞患者的临床病程更为缓慢。基因表达研究表明，表达未突变Ig的CLL细胞可以通过相对较小的基因亚群的差异表达来与更惰性的类型区分，其中一个基因亚群编码ZAP-70。我们发现表达这种蛋白酪氨酸激酶的CLL细胞比不表达ZAP-70的CLL细胞通过B细胞受体（BCR）复合物具有更熟练的信号传导。使用编码野生型或突变型ZAP-70的腺病毒载体进行转染研究，有助于确定ZAP-70是否在BCR信号中发挥功能作用，从而起到治疗作用

We have made significant progress in defining the use of immunoglobulin (Ig) variable region genes (V genes) in chronic lymphocytic leukemia (CLL). Prior studies suggesting restriction in the Ig V gene repertoire have been extended, revealing that the Ig expressed in CLL possibly are selected for their ability to bind multiple self-antigens with low affinity. We generated transgenic mice with B cells that express such polyreactive human IgM and found that these cells can differentiate into marginal zone (MZ), memory-type B cells. Such MZ B cells share gene expression profiles with that of CLL cells. These and other newly developed transgenic mouse models of CLL will allow us to evaluate whether Ig receptor signaling plays a role in leukemogenesis and/or disease progression. Recent studies have revealed that patients with CLL cells expressing mutated Ig have a more indolent clinical course that those with CLL cells that express unmutated Ig genes. Gene expression studies revealed that CLL cells expressing unmutated Ig could be distinguished from the more indolent type through the differential expression of a relatively small subset of genes, one of which encodes ZAP-70. We found that CLL cells that express this protein tyrosine kinase have more proficient signaling via the B cell receptor (BCR) complex than CLL cells that do not express ZAP-70. Transfection studies using adenovirus vectors encoding wild type or mutant forms of ZAP-70 are helping to resolve whether ZAP-70 plays a functional role in BCR signaling that can serve as a therapeutic target in this disease. Finally, work on this project has led to development of strategies for inducing anti-leukemia immune responses via the use of CLL cells that are activated via CD40-ligation. Phase I and early phase II clinical trials using recombinant adenovirus vectors encoding a recombinant CD40-ligand (Ad-CD154) are direct manifestations of work performed on this proposal. Further studies could enable us to refine this approach toward development of truly effective immune therapy for patients with this disease.