New study shows the ability of CD8+ cytotoxic
T cells to penetrate a large target, which opens avenues to destroy solid
cancers.A new study has provided novel evidence on the capability of the immune
system to eliminate large parasite-filled cysts associated with chronic
Toxoplasma gondii (T. gondii) infection by utilising the aggressive invader
activity of cytotoxic T cells. The findings indicate these T cells may also
prove effective for attacking other sizable targets including solid cancers.
“The present study provided clear evidence
that the immune system has the capability to attack and eliminate the tissue
cysts of T. gondii,†said lead investigator Dr Yasuhiro Suzuki, of the Department
of Microbiology, Immunology and Molecular Genetics, University of Kentucky
College of Medicine. “This sheds light on the possibility of developing a
vaccine to activate these invasive cytotoxic T cells to prevent the
establishment of chronic infection with this parasite. This vaccine may also be
applied to individuals chronically infected with T. gondii to eradicate
existing tissue cysts of the parasite and cure this widespread chronic
infection.
“This study also suggests the possibility of
developing a new cancer immunotherapy that can be used to eliminate various
types of solid cancers by activating the invasive cytotoxic T cells that
specifically attack and penetrate into the target cancers.â€
The scientists investigated the effects of an
injection of CD8+ immune T cells purified from the spleens of chronically
infected mice, into mice that had ingested multiple T. gondiicysts. A few days
after the T-cell injection, numbers of T. gondii cysts fully invaded by the T
cells were found in the brains of the mice that received the injection of the
immune T cells.
The T-cell-invaded cysts displayed structural
signs of deterioration and destruction and granular structures appeared
intensely positive for granzyme B, a major cytotoxic protein secreted by cytotoxic
T cells. These granular structures were detected in association with T. gondii
bradyzoites.
Furthermore, the bradyzoites within the
destroyed cysts were located within accumulated scavenger cells, including
microglia and macrophages. The investigators also showed that perforin was
necessary for the CD8+ T-cell invasion and cyst elimination process.
“The invasion of the T cells into tumours
could induce an infiltration of large numbers of phagocytic cells capable of
attacking the cancer cells as was observed against T. gondii cysts,†added Dr.
Suzuki. “An effective activation of the penetrating capability of cytotoxic T
cells, which specifically recognise the target solid cancers, will most likely
become a powerful therapeutic approach applicable to various types of solid
cancers.â€
From source: https://www.drugtargetreview.com/news/46333/cytotoxic-t-cells-destroy-targets-large-mass/
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