Immune System: Adaptive Immune System Does Not Generate A Successful Response Without Instruction And Help From The Innate Immune System
: Emerging research by scientist from University of Rochester-New York show how different cells in the immune system work together, communicate, and in the case of cells called neutrophils bring about their own death to help fight off infections.
The study findings are published in the journal: Nature. Immunology https://www.nature.com/articles/s41590-020-0746-x
Dr Minsoo Kim, Ph.D., a Professor of Microbiology and Immunology at the University of Rochester Medical Center (URMC) and senior author of the study told Thailand Medical News, "This study represents an important paradigm shift and shows that the adaptive immune system doesn't generate a successful response without instruction and help from the innate immune system. The research indings reveal, for the first time, how different immune cells work together, and even sacrifice themselves, to accomplish the same goal of protecting the host from the viral infection."
The research findings could also have important implications for the development of vaccines and anti-viral therapies.
The early recruitment of neutrophils from the blood to sites of tissue infection is a hallmark of innate immune responses. Little is however, known about the mechanisms by which apoptotic neutrophils are cleared in infected tissues during resolution and the immunological consequences of in situ efferocytosis.
Utilizing intravital multiphoton microscopy, we show previously unrecognized motility patterns of interactions between neutrophils and tissue-resident phagocytes within the influenza-infected mouse airway. Newly infiltrated inflammatory monocytes become a chief pool of phagocytes and play a key role in the clearance of highly motile apoptotic neutrophils during the resolution phase. Apoptotic neutrophils further release epidermal growth factor and promote the differentiation of monocytes into tissue-resident antigen-presenting cells for activation of antiviral T cell effector functions.
These results suggest that the presence of in situ neutrophil resolution at the infected tissue is critical for optimal CD8+ T cell–mediated immune protection
Dr Kim added, "The immune system consists of several different types of cells, all acting in coordination. These findings show that cells called neutrophils play an important altruistic role that benefits other immune cells by providing key resources for their survival and, in the process, enhancing the body's immune response against a virus."
The neutrophils are a key component of the innate immune system, the part of the body's defenses that is always switched on and alert for bacterial and viral invaders. The vast majority of white cells circulating in blood are neutrophils and, as a result, these cells are the first on the scene to respond to an infection.
It must be noted however, neutrophils are not fully equipped to eliminate a viral threat by themselves. Instead, when the respiratory tract is infected with a virus like influenza or SARS-CoV-2 that causes the COVID-19 disease, a large number of neutro
phils rush to the infection site and release chemical signals.
This subsequently triggers the production of specialized T cells, which are part of the body's adaptive immune system, which is activated to produce a more direct response to specific infections.
Upon being mobilized in sufficient quantities, a process that typically takes several days, these T cells target and ultimately destroy the infected cells.
Interestingly the new study, which was conducted in mice infected with the flu virus, shows that in addition to jump-starting the adaptive immune response, neutrophils have one more important mission that requires that they sacrifice themselves.
It was observed that as T cells arrive at the infection site, the neutrophils initiate a process called apoptosis, or controlled death, which releases large quantities of a molecule called epidermal growth factor (EGF). EGF provides T cells with the extra boost in energy necessary to finish the job.
Dr Kim and his colleagues point out that this new understanding of how the immune system functions opens the door to potential new methods to intervene and optimize the collaboration between different immune cells during viral infection. These efforts could ultimately lead to more effective vaccines and anti-viral therapies for respiratory infections like the flu and coronavirus.
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