( A scientific discovery by Fox Chase Ca...)How 'memory' T cells curb the spread of viruses throughout the body

A scientific discovery by Fox Chase Cancer Center researchers helps explain how “memory” T cells protect the body from viral diseases. The research published today in Proceedings of the National Academy of Science Online Early Edition shows lymph nodes are not just organs where immune cells reside and proliferate, but also are the sites where a major fight against the spread of an invading virus occurs.

After becoming sick from many viruses, the body becomes “immune” (protected) from recurrence of the same disease. This is why before vaccines were developed, childhood diseases such as measles and mumps occurred only once in a lifetime. The immunity occurs when the immune system produces cells called lymphocytes that specifically attack and eliminate the virus at the time of infection. After the infection subsides, most of the lymphocytes die but some remain in the body as “memory lymphocytes” and protect the body from recurrence of the disease. Similarly, vaccines induce the production of memory lymphocytes, but without causing disease.

While scientists have long known the role of antibodies in protection, whether memory cells, known as CD8 T cells, could prevent viral diseases has been debated. The new work by Fox Chase virologist Luis J. Sigal, D.V.M., Ph.D., and his Fox Chase colleagues in the virology and pathology programs, provides the basis whereby memory CD8 T cells do, in fact, prevent viral diseases.

CD8 T cells normally reside in lymphoid organs such as the lymph nodes. It was thought that to protect from disease, memory CD8 T cells needed first to multiply in the lymph nodes and then migrate through the blood to kill infected cells at the site where the virus entered the body (most commonly the skin, the lungs or the gut). This process of lymphocyte multiplication and migration may take several days while viruses multiply and spread quicker. Sigal’s work shows the CD8 T cells can protect from viral disease without the
'"/>

Source:Fox Chase Cancer Center