"It's nice that the T cell learns to recognize the antigen, but that doesn't get rid of the microbe that has entered the body," von Andrian said. He traced the path of the educated T cells leaving the lymph node, when they become known as effector cells. In addition, von Andrian addressed how these T cells kill those cells they identified as harboring a pathogen without going on a rampage and annihilating everything in sight.
"There must be a control mechanism that can keep these cytotoxic cells in check," von Andrian noted. The immune system does this by creating regulatory T cells to control the effector cells, he said. Previous research had shown that the regulatory T cells can also receive their education in the lymph node before proliferating and entering the blood stream.
May lead to vaccines
"The events I have described are at the heart of any vaccination," von Andrian said. Many pathogens take advantage of the lymph system to gain access to the body, he noted, including pathogens used in biological warfare, such as anthrax, or yersinia pestis, the agent that causes the plague.
Bubonic plague, for instance, starts with a flea that deposits a few bacteria, which travel via the lymphatic system to the lymph node and proliferate to huge numbers. One of the puzzles von Andrian has been working on, is how foreign invaders manage to proliferate in the very area, the lymph node, where the immune system is marshaling its troops.
"So understanding how these (foreign) cells survive in the lion's den of the lymph node might allow us to develop strategies to combat infections," von Andrian said. "Somehow, they do this without ringing the alarm bells. Possibly we could manipulate the process to ring the alarm bell for the immu
Source:American Physiological Society