Lck is important in helping "naive" T cells -- those cells that have never been exposed to a particular pathogen -- capture the receptor template of the invading agent and store it for future reference. Among the millions of naïve T cells, there are a few that are primed for active duty against an individual infectious agent. Following infection or vaccination, Lck initiates a biochemical chain of events that vastly increases the number of T cells that march off to combat the invader.
After the infection subsides, the number of T cells marshaled to fight that agent decreases dramatically. But a smaller subset, known as "memory" cells, retains the imprint of its previous encounter should the pathogen make a return appearance.
According to the study, while Lck primes naïve cells to fight a pathogen, it is not required by memory cells, which initiate the fast and furious response when that same pathogen comes calling again years later. Unlike naïve T cells, which are confined to the lymphatic system, memory T cells are found everywhere in the body, enabling them to sense and react more quickly when an infectious agent is reencountered.
"Now we know one of the reasons we get such a quick response and clearance (of the pathogen) with reinfection," Suresh explains. "If you increase the size of your army, you can clear your enemies faster. The memory T cells are greater in number and they are more potent."
The new insight could help refine therapeutic targets to treat autoimmune diseases and may inform new strategies for suppressing T cell response after transplantation. Now, transplant patients require life-long regimens of drugs to suppress immune response to the foreign cells in the donated organ.