T cells are the immune system’s guard dogs, attacking pathogens while leaving the body’s own cells alone. Now researchers have mapped the process that T cells use to tell friend from foe.
The process resembles how a person at a party might recognize someone they don’t know well by using that person’s strong handshake or distinctive voice to supplement their recollection of facial features. Details are reported in the journal Immunity.
The researchers found that T cell receptors—molecules located on the surface of the T cell—first bind with the antigen on the pathogen-invaded cell. That initiates a signaling process which leads a co-receptor on the T cell to also bind with the molecule that presents the antigen, amplifying the effect.
“We show for the first time the important role of the co-receptor in contributing to the discrimination process that takes place in the T cell,” says Cheng Zhu, a biomedical engineering professor at the Georgia Institute of Technology and Emory University. “This is a cooperative binding process with the co-receptor co-engaging with the T cell receptor. This cooperative binding has a synergistic effect that amplifies the action.”
The resulting binding, which then triggers the body’s defensive activities, is stronger than the sum of the individual binding that would result from the T cell receptor and CD8 co-receptor operating independently.