November 28, 2005

Nanomedicine: Using nanotech to gain understanding and possibly controlling T-cells

In a new experiment, published last week in Science, Jay Groves and colleagues at the University of California at Berkeley designed an artificial membrane that allows them to begin to answer how receptors on t-cells effect and control immune system response. The membrane has proteins that are constricted in a specific region. When receptors on the T cell bind to the proteins on the artificial membrane, the receptors are constrained to these specific geometric patterns, allowing a closer examination of the effects of the patterns.

Previously, scientists thought that the growing number of receptors triggered a strong T cell activation. But when Grove and his team blocked the migration of T cell receptors by binding them to locked-in proteins on the artificial membrane, which acts like an infected cell, they discovered it was the position of the receptor that actually controlled the response.

The technology eventually could be used to develop cell-based drug screens in order to determine how candidate compounds affect immune-cell signaling. For example, scientists could expose cells bound into an artificial membrane to different drugs, and observe how those drugs affect T cell clustering. "Understanding how [cell signaling] works is a big component of learning how to control it with drugs," says Groves.

The findings could also lead to new treatments for auto-immune diseases, in which the immune system attacks the body's own proteins. "Effective treatments for auto-immune diseases like Rheumatoid arthritis turn down immune response, but this leaves the patient more vulnerable to infection," says Michael Dustin, an immunologist at the Skirball Institute of Biomolecular Medicine at New York University, who collaborated on the Berkeley project. "You could use patterned particles to make more specific treatments, but first we need to learn the language."

Once researchers experimentally determine the signals associated with different patterns, it may be possible to build a particle with pre-patterned receptors that direct T cells to turn off the immune response, says Dustin. If the pattern was specific enough to turn off the immune response in particular organs, such as the brain in multiple sclerosis or the joints in rheumatoid arthritis, the rest of the immune system could still function effectively to fight viral invaders.

The technique also has blue-sky applications, going far beyond the immune system. "If you can make artificial surfaces that communicate with cells on a sophisticated level, you could make devices that tell cells what to do," says Groves. "You could get cells to generate energy or do a chemical conversion; it would be tremendous."

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