Technique bolsters dendritic cell vaccines
Researchers have developed a technique that allows dendritic cell vaccines, which are being investigated as potential cancer vaccines, to activate the immune system more successfully.
Dendritic cells are transformed into cancer vaccines by mixing them with
genetic material from a tumour. The modified cells are then able to present
the tumour antigens to a patient’s killer T cells for destruction.
However, such modified cells do not activate the immune system as well
as expected.
“Dendritic cell vaccines have shown promise in battling cancers
in laboratory studies, but they have not met with quite the success in
the clinical
trials that laboratory studies suggest they should,” said study
author Yiping Yang, assistant professor of medicine and immunology at
Duke University Medical Centre, Durham, North Carolina. “Our study
highlights what element is missing in dendritic cell vaccines that prevents
them from activating the immune system, and we’ve shown how to
insert that element.”
Dr Yang and colleagues created an animal model that mimics the T-cell
tolerance seen in cancer patients and then compared the behaviour of
dendritic cell vaccines with that of viral vaccines, known to activate
T-cells without difficulty.
The researchers observed that viral vaccines were able to activate an
immune response readily because of the presence of viral proteins called “pathogen-associated
molecule patterns” (PAMPs). These molecules are unique to pathogens
and are viewed as foreign by a patient’s T cells. By contrast,
the dendritic cell vaccines were not viewed as sufficiently foreign and
so failed to provoke killer T cells to react effectively.
By mixing dendritic cell vaccines with PAMPs the researchers were able
to induce a more forceful response. They plan to test the concept of
bolstered dendritic cell vaccines in lymphoma patients within the next
few years.
The study is published
online in Nature Immunology (4 April 2004). |
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