Leukocyte Migration chapter 15 and Inflammation
FPO part of the body to another. This is espe- cially true of lymphocytes, which circulate Mcontinually in the blood and lymph and, in common with other types of leukocytes, migrate into the tissues at sites of infection or tissue injury. This recirculation not only in- creases the chance that lymphocytes specific for a particular antigen will encounter that antigen but also is critical to Lymphocytes Attached to the Surface of a High-Endothelial Venule development of an inflammatory response. Inflammation is a complex response to local injury or other trauma; it is characterized by redness, heat, swelling, and pain. Inflam- Lymphocyte Recirculation mation involves various immune-system cells and numer- Cell-Adhesion Molecules ous mediators. Assembling and regulating inflammatory responses would be impossible without the controlled Neutrophil Extravasation migration of leukocyte populations. This chapter covers the Lymphocyte Extravasation molecules and processes that play a role in leukocyte migra- tion, various molecules that mediate inflammation, and the Chemokines—Key Mediators of Inflammation characteristic physiologic changes that accompany inflam- Other Mediators of Inflammation matory responses. The Inflammatory Process