Blocking immune system protein can hasten newer cancer treatments

September 30th, 2008 - 4:28 pm ICT by IANS  

Washington, Sep 30 (IANS) Scientists have found that blocking an immune system protein, like the C5a that shields tumour growth, can expedite newer cancer treatments. C5a is part of one of the body’s complex of defences against pathogens. When activated, these proteins rid the body of microbes and foreign cells. Many treatments are aimed at boosting the immune system to kill tumours.

“We found that in some conditions, the complement system (C5a) can promote tumour growth, depending on the specific tumour and the specific environment in which the tumours are developing,” said John Lambris, professor of research medicine, Pennsylvania University School of Medicine.

However, Penn researchers found that in a mouse model, activation of the complement system in tumour tissue leads to the generation of C5a, which recruits myeloid-derived suppressor cells (MDSC) to tumours. These MDSCs block the function of CD8+T cells, which would normally dismantle a tumour.

Researchers also found that blocking the C5a receptor on cell surfaces impairs tumour growth at the same rate of Paclitaxel, a chemotherapy drug. This discovery could lead to new cancer treatments with far fewer side effects than chemotherapy, surmise the investigators, according to a Pennsylvania University press release.

“Researchers are trying to introduce immune therapies and anti-tumor vaccines, but most of these vaccines fail,” said Lambris. “We show in this study a possible mechanism how to overcome this problem.” Lambris and his team are conducting studies that apply the approaches outlined in this paper to five models of cancer.

These findings appeared online this week in Nature Immunology.

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