T-cells, the elite guard of the immune system in humans and othermammals, ignore normal biologic protocol and swing into high gearwhen attacked by certain fast-moving bacteria, reports a team ofresearchers led by a UC Davis immunologist.
The description of this previously undefined immune pathway providesinformation vital for designing vaccines and medicines to prevent ortreat deadly infectious diseases caused by bacteria such asSalmonella and Chlamydia. The results from this recent mouse-basedstudy will be reported online Feb. 6 in the journal Immunity.
"Our study shows that the body's immune system functions verydifferently when it faces a rapidly growing pathogen like Salmonellaor Chlamydia," said immunologist Stephen McSorley, an associateprofessor at UC Davis' Center for Comparative Medicine, whichinvestigates diseases that afflict both humans and animals.
"The strict rules that normally govern T-cell activation are relaxedso that the host animal has the best possible chance of a maximalresponse and ultimately staying alive," he said.
T-cells, which belong to a group of white blood cells calledlymphocytes, normally respond defensively to the presence ofsubstances known as antigens, which are produced by invading bacteriaand viruses. It's widely known that T-cells launch an immune defensewhen they recognize specific antigens.
However in this study, the researchers demonstrated in the mouse thatcertain T-cells don't require the presence of specific antigens tolaunch an effective immune response. During fast-moving Salmonellaand Chlamydia infections, a cascade of other antimicrobialinteractions occur that trigger these T-cells to respond defensivelyto the bacterial attacks, even without the presence of specificantigens.
The researchers also showed that when this defensive pathway wasdisrupted during Salmonella infection, the mice had greaterdifficulty getting rid of the bacterial disease.
The researchers note that further study is needed to determine ifthis newly defined antimicrobial pathway also can provide protectionagainst co-infections by multiple disease-causing microbes.
Source: University of California - Davis