A visual technique of chemotactic assessment for pharmacological studies.

A visual assay of chemotactic response was performed by measuring the extent of the migration of polymorphonuclear leukocytes (PMN) collected from the rat pleural cavity toward a dying cell. Various types of cells (erythrocytes, PMN, or monocytes) may be destroyed by means of an argon laser, and the process may be visualized under a phase-contrast microscope (necrotactic phenomenon). This experimental model may simulate pathological events that occur in damaged tissues, and it permits the study of cellular migration during inflammatory diseases. This method did not seem to involve chemokinetic effects, but instead represented a true measure of chemotaxis. A numeration of the migrating PMNs at t = 0 and t + 10 min after cell lysis allowed a statistical analysis and the use of this phenomenon for pharmacological studies. The modification of rat PMN chemotaxis by cholera toxin, substance P, and a synthetic muramyl dipeptide are presented as examples of the use of this technique.