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'How immune cells kill tumours decoded'

Press Trust of India  |  Los Angeles 

Researchers have identified a mechanism that could help determine whether a patient will respond to

Ideally, the immune system identifies as threatening elements and deploys immune cells (T cells) to find and kill them, according to the study published in the journal Cell Reports.

However, cells have evolved to employ a protein called PD-L1 to blind T cells from carrying out their functions and evade immune defences.

PD-L1 protects cells by activating a "molecular brake" known as PD-1 to stop T cells.

In important therapeutic progress, developed to block PD-L1/PD-1 have been clinically proven to benefit certain patients.

Yet why some patients do not respond to such therapy has remained a mystery.

Now, researchers from the in the US and the have uncovered some clues.

They discovered an unexpected twist in the versus T cell battle. Some tumour cells display not only their PD-L1 weapon, but also the PD-1 "brake."

This simultaneous expression leads PD-1 to bind and neutralise PD-L1 on the same tumour cell. Thus, the PD-L1 on these tumour cells can no longer engage the PD-1 brake on T cells.

"It's a very exciting finding. Our study uncovered an unexpected role of PD-1 and another dimension of PD-1 regulation with important therapeutic implications," said Enfu Hui from UC

This study suggests that patients with high levels of PD-1 on tumour cells may not respond well to the blocking because the PD-1 pathway is self-cancelled.

In these patients, mechanisms other than PD-L1/PD-1 are likely employed by the to escape from immune destruction.

Looking to extend the potential of the finding, Hui and his colleagues are now seeking to determine additional mechanisms of "self-cancellation" at the interface of the tumour and immune cells.

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)

First Published: Wed, July 11 2018. 13:55 IST