Borie D C, Cramer D V, Shirwan H, Wu G D, Rodriguez O, Chapman F A, Makowka L
Department of Surgery, Cedars-Sinai Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Transplantation. 1995 Dec 27;60(12):1504-10. doi: 10.1097/00007890-199560120-00023.
The early phases of the rejection of xenografts exchanged between closely related species are dominated by a vigorous humoral immune response. We have recently used a linker-mediated polymerase chain reaction (LM-PCR) to generate Ig heavy and light chain-specific cDNA libraries to examine the Ig gene control of a prototypic IgM monoclonal antibody, HAR-1, that causes the hyperacute rejection of hamster xenografts. Recombinant clones from the library were screened directly from bacterial colonies by PCR and the nucleic acid sequences of the clones established. Our results demonstrate that the HAR-1 hybridoma is encoded by Ig VH and JH genes in a germline configuration. Comparison of the cDNA sequence for HAR-1 VH with the germline equivalent of this gene isolated from newborn LEW liver (provisionally designated VHHAR-1) showed that the two VH sequences share a nucleic acid identity of 99.3%. Similarly, the HAR-1 monoclonal uses a Ig JH gene that is 98.2% identical with the JH1 nucleic acid sequence available in the GeneBank. The use of Ig VH and JH genes in a germline configuration is similar to that seen with polyreactive natural antibodies to infectious agents and autoantibodies. These humoral responses are thought to be the result of the stimulation of a T cell-independent subset of B cells, the B-1a/B-1b subset, that is responsible for producing antibodies that serve as a primitive humoral (natural antibody) defense mechanism against infectious diseases. Our results suggest that the humoral component of the rejection of xenografts in the hamster-to-rat model may represent the stimulation of this type of B cell antibody response by xenogeneic target antigens that share antigenic epitopes with bacteria and other infectious agents.
在亲缘关系相近的物种间进行异种移植时，早期的排斥反应主要由强烈的体液免疫反应主导。我们最近利用连接介导的聚合酶链反应（LM-PCR）构建了免疫球蛋白重链和轻链特异性的cDNA文库，以研究一种原型IgM单克隆抗体HAR-1的免疫球蛋白基因调控情况，该抗体可引发仓鼠异种移植的超急性排斥反应。通过PCR直接从细菌菌落中筛选文库中的重组克隆，并确定克隆的核酸序列。我们的结果表明，HAR-1杂交瘤由处于种系构型的免疫球蛋白VH和JH基因编码。将HAR-1 VH的cDNA序列与从新生LEW大鼠肝脏中分离出的该基因的种系对应序列（暂命名为VHHAR-1）进行比较，结果显示这两个VH序列的核酸同一性为99.3%。同样，HAR-1单克隆抗体使用的免疫球蛋白JH基因与基因库中可用的JH1核酸序列的同一性为98.2%。使用处于种系构型的免疫球蛋白VH和JH基因的情况，与针对感染因子的多反应性天然抗体和自身抗体类似。这些体液反应被认为是由B细胞的一个不依赖T细胞的亚群，即B-1a/B-1b亚群受到刺激所致，该亚群负责产生作为针对传染病的原始体液（天然抗体）防御机制的抗体。我们的结果表明，仓鼠-大鼠模型中异种移植排斥反应的体液成分可能代表了异种抗原对这类B细胞抗体反应的刺激，这些异种抗原与细菌及其他感染因子共享抗原表位。
