永利平台注册

Technology : T cell trickery transforms transplants

作者:劳疼蛋    发布时间:2019-02-27 01:08:02    

By Andy Coghlan PATIENTS undergoing organ transplants at a hospital in the US have begun a pioneering course of treatment aimed at preventing rejection of their new organs. By reprogramming the patients’ immune systems before they receive the organs, the surgeons hope to trick the patients’ bodies into accepting the new organs as “self”. If the reprogramming works, donor organs would not even need to match transplant patients’ tissue. The system, pioneered by David Sachs of the Massachusetts General Hospital (MGH) in Boston, could also mean people with new organs will be able to survive without the drugs that prevent their immune systems from attacking the transplant Surgeons led by Benedict Cosimi at the MGH are testing Sachs’s three-stage treatment regime on patients. The “AlloMune” regime, which is now being developed by BioTransplant, a company based at Charlestown, Massachusetts, has already been tested successfully in primates in previous trials. Patients will first receive a rat antibody codenamed BTI-322. This antibody, discovered by researchers at the Catholic University of Leuven in Belgium, neutralises mature T cells, the sentinels of the body’s immune system. “These T cells form the body’s front line of defence against foreign material entering the body,” says Elliot Lebowitz, the president of BioTransplant. Normally, they would register a transplanted organ as foreign and orchestrate its destruction. In experiments on primates, doses of antibody over 10 days inactivated all mature T cells in the animals’ bloodstreams. When patients have undergone similar “purges”, they will receive radiation treatment to create a space in their bone marrow where surgeons will transplant bone marrow from the organ donor. This transplanted tissue creates a “chimeric” bone marrow containing cells from both patient and donor. This is the key to reprogramming the patient’ immune system. The process takes place in the thymus, the gland where T cells are primed to attack “foreign” material, or taught not to attack native tissue. Cells from the chimeric bone marrow arrive at the thymus as they begin to evolve into T cells. In the thymus, this new set of T cells is “taught” to accept tissue from both the host and donor as “self”. “The original immune system is inactivated and a new one created in its place,” says Lebowitz. Finally, patients will receive the organ itself. The researchers hope that the new immune system will always accept the organ as self. As a precaution, patients will receive the usual immunosuppressive drugs for a month or so to prevent rejection. Experiments at MGH have shown that the original arsenal of T cells reappears in the new immune system, minus cells that would have attacked the donor tissue. Likewise, the new immune system is primed to destroy anything that threatens the newly implanted tissue. Lebowitz says that details of the experiments are being kept secret to protect the identity of the patients. But he expects the first results to be made public some time next year. “If it works, it’s a really big deal,” he says. Not only are immunosuppressive drugs expensive,

 

Copyright © 网站地图