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Key Molecule in Immune Surveillance System Found

Posted on: Tuesday, 7 September 2004, 06:00 CDT

Tokyo, Sept. 8 (Jiji Press)--Japanese scientists have found a molecule that plays a crucial role in the immunological surveillance system, and are now considering developing a vaccine immunotherapy to treat cancer patients.

Immune cells travel throughout the body searching for hints of infection or injury. The cells exit the bloodstream in response to chemical cues that tell them "stop and get out of the stream." Their exit from the bloodstream is accomplished by a rapid change in their ability to stick to other cells. But the molecule governing the high trafficking capability has remained unknown.

The Japanese scientists, led by Prof. Tatsuo Kinashi of Kyoto University, discovered that lymphocytes in mice lacking a protein called RAPL are unable to adhere to tissues and fail to arrive at locations necessary for generating immune responses.

Last year, the same scientists found that an intracellular protein called Rap1 acts as an "ON-OFF" switch to control the stickiness of integrin, adhesive protein, under the instruction of RAPL.

When RAPL sets Rap1 to the "ON" state, it induces integrins to expose their sticky ends and let immune cells leave the bloodstream. In the "OFF" state, the cells continue traveling in the stream.

Through this latest experiment, RAPL was also found to be "a crucial immune cell trafficking regulator essential for immunosurveillance," the scientists said. Further research "may ultimately lead to the development of therapeutic treatments for immune diseases," as well as cancer, they said.

Details of the study were published online Wednesday by British journal Nature Immunology.END

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