Scientists would then draw blood from the animal to determine if antibodies had formed around the vaccine's proteins which meant the vaccine was working. The resulting experiment would often take weeks to conclude. The new method allows researchers to physically follow the two types of lymphocytes that help create those antibodies. Immune responses begin in the lymph nodes of an organism, where B lymphocytes and T lymphocytes find each other and bind together. Then, T lymphocytes send a chemical message to the B lymphocytes, which begin to make the antibodies.
Researchers can examine the early phases of antibody production, with the new procedure.
Using specific experimental mice who have been injected with a vaccine, the scientists later remove and examine the mouse's lymph nodes. The vaccine is tagged with enzymes that produce color so when antibodies are produced in the lymph nodes, it is visible. By staining specific lymphocytes, they can determine the location and number of responses, and how the vaccine is working. As a result, researchers are able to observe effectiveness as quickly as two days after immunizing the mice. Jason Cuyster, associate professor of microbiology and immunology at the University of California at San Francisco, said the new method is important because it is the first demonstration in which scientists can see the events happening in the lymph nodes.