Washington: For the first time, scientists have found that immune cells prevalent in the skin are more protective in fighting infection than those in the bloodstream.
The findings, published in the journal Nature, could lead to develop a new class of vaccines with improved preventative and therapeutic efficacy that can have a major impact on human health, the researchers said.
In the study, a team at the Harvard Medical School found that when vaccinia virus delivered to the skin, viral-specific T cells, called TREMs (T Resident Effector Memory cells), were not just recruited to the infected site, but also to all areas of the skin.
These TREMs remained in skin and gave rapid and effective protection against a second infection from the same virus.
While skin was used as a model system in the study, the results are relevant to epithelial cells in the lungs, GI tract, and other epithelial tissues that are sites of viral entry to the body, the researchers said.
The findings challenge immunological dogma by suggesting that the most important elements of T cell memory and immunity to infectious diseases may reside in skin and other epithelial tissues rather than by circulating T or B cells in the blood.
The results suggest that vaccines to generate TREM can be optimised by delivery through epithelial tissues for a potentially more effective immune response than is achieved with conventional vaccine injection.
Conventional vaccines are typically focused on optimising the B cell arm of the immune system to create disease-fighting antibodies.
"But this study shows that a more effective path to immunity may be to engage this newly discovered part of the T cell arm of the immune system through a population of powerful immune cells that we now know reside in the skin, lung, gut, and other epithelial tissues," Dr Thomas Kupper, who led the study, said.
This study also explains why novel vaccines administered to upper layers of the skin in pre-clinical models have better preventative and therapeutic efficacy over traditional vaccine injected into the muscles or bloodstream, the scientists said.
"This ground breaking research provides a major opportunity to develop a new class of vaccines with improved preventative and therapeutic efficacy that can potentially have a major impact on human health," said Eric Stromquist, president of TREM Rx, a biotechnology company that makes novel vaccines delivered to the skin.
"We are committed to translating this new understanding of protective immunity to the design of novel vaccines for a wide range of applications, including important infectious diseases and cancers," Stromquist added.