The research, reported in the December 15, 2006 issue of the journal Science, describes the elements of the "internal compass" that neutrophils use to detect and migrate towards chemoattractants, markers of infection and inflammation that are released from bacteria and inflamed tissues.
"These findings solve the long-standing puzzle of how neutrophils find their way and move toward sites of injury or infection in the body," said senior author Wolfgang Junger, Ph.D., adjunct professor of surgery at UCSD Medical Center.
His team set out to identify the key mechanisms of signal amplification that must occur in order for neutrophils to detect the low-level activating signals (chemoattractants) sent out by bacteria at injury sites. They found that neutrophils possess a built-in amplification system that is an integral part of the internal compass the cells use to locate the source of chemoattractants. At the core of the amplification system is the chemical adenosine triphosphate (ATP).
The chain of events necessary to direct the neutrophils toward its goal begins when ATP is released from the region of the cell surface closest to the source of chemoattractants. Next, ATP binds to a nucleotide receptor called P2Y2 on the cell surface, a step critical to position the cells in the direction of the source of chemoattractants.
Once this internal compass has been activated, ATP is converted by the cells to adenosine, which in turn activates A3 adenosine receptors concentrated at the front of cells, providing the signal to move toward th
Source:University of California - San Diego