ABSTRACT
This chapter explores some of the data available to support a role for mast cells as initiators of leukocyte recruitment with a particular focus on leukocyte rolling and the selectins. It describes some of the areas of controversy and emphasizes areas that require further investigation. The most common method used to study leukocyte behavior in the microcirculation is an approach termed intravital microscopy, which permits direct visualization of the lumen of microvessels. It has been well established that leukocyte infiltration is a multistep mechanism that requires that leukocytes moving at very high speeds in the mainstream of blood make initial transient contact with endothelial cells lining the vessel wall and roll along at a greatly reduced velocity relative to red blood cells. Oxidative stress is a common feature of many different inflammatory diseases. If oxidants such as superoxide can activate mast cells to induce leukocyte rolling, then inflammatory conditions with an underlying superoxide component may also involve mast cells.
