Biological aspects of leukotactic factors.

Quantitation of leukotaxis involves direct visualization of migrated cells either as total cell numbers or according to depth of penetration of cells into filters. Newer approaches utilize radioactively labeled cells or movement in gel. Considerable controversy exists regarding the structural attributes of chemotactic activity, although synthetic peptides emphasize the importance of primary structure. Leukotactic factors, both complement-derived and lymphocyte-generated, have been found in many conditions both in vitro and in vivo. There is increasing evidence that the leukotactic system plays an important role in the pathogenesis of inflammation.