Published in the Open-Access journal PloS Pathogens on August 4th, researchers showed that cells of the innate immune system are capable of “memory”, and of mounting rapid protection to an otherwise lethal dose of live vaccinia virus. The study contests prior belief that only B cells and T cells are able to store memory to fight off future infection.
The discovery, by researchers from Beth Israel Deaconess Medical Center, Harvard Medical School, Hebrew University and Duke University, has potentially crucial repercussions for the design of future vaccines, HIV in particular.
The Immune system builds Immunological “memory” in order to react more efficiently to pathogens (such as bacteria and viruses) that the host organism has come across previously. Immunological “memory” traditionally was thought to exist in the cells of the adaptive arm of the immune system (B cells and T cells) that reveal highly specific fragments of pathogens through unique receptors.
Dr. Geoffrey Gillard who led this study, demonstrates that an innate population of cells, known as natural killer (NK) cells form “memory” to infections from vaccinia virus, although lacking receptors of traditional “memory” cells. Immunodeficient mice had “memory” NK cells transferred into them, which was sufficient in protecting the mice against a usually lethal exposure to vaccinia virus.
Because the NK cell population has no receptors allowing B and T cells to develop highly specific “memory” responses to pathogens, important questions are raised in the study regarding the manner in which “memory” NK cells are capable of recognizing viruses upon a second encounter.
Comprehending how innate “memory” functions will be crucial for combining this property into more efficient vaccines, specifically as part of a HIV vaccine. The ability to respond very rapidly most notably in the properties of NK memory, could be beneficial in exerting early control of the HIV infection by restricting the ability of the virus to overpower the host immune system in the initial stages of infection.
Written by Grace Rattue