In a study published in the online edition of the journal Blood on April 25, Ofer Levy, MD, PhD and colleagues in Children's Division of Infectious Diseases show that the newborn immune system functions differently than that of adults, but that one portion of the immune response is fully functional and can be harnessed to boost immunity in these tiny infants, possibly making infections like respiratory syncytial virus, pneumococcus, pertussis, HIV and rotavirus much less of a threat.
For about a decade it's been known that people's first line of defense against infection is a group of receptors known as Toll-like receptors (TLRs) on the surface of certain white blood cells. Functioning like an early radar system, TLRs detect the presence of invading bacteria and viruses and trigger production of "danger signals" ?proteins known as cytokines that trigger other immune cells to mount a defense against the infection. People have 10 different kinds of TLRs, and Levy's team decided to examine how well they function in newborns by studying white blood cells from their cord blood.
"We found that when most Toll-like receptors are stimulated, newborns' immune responses are very impaired," Levy says. "But there was one important exception."
Levy's team, including Harvard graduate Eugenie Suter and senior author Michael Wessels, MD, showed that one TLR, known as TLR8, triggered a robust immune response in a group of white blood cells (called antigen-presenting cells) that is crucial for vaccine responses. When TLR8 was stimulated by various agents that mimic viral antigens, the cells produc
Source:Children's Hospital Boston