PMN chemotaxis in response to IL-8, MGSA, and NAP-2. Chemotaxis of PMN induced by increasing concentrations of IL-8, MGSA, or NAP-2 was measured in the Boyden chamber system. Results are expressed as the number of migrated cells detected in the lower compartment of the chamber after 1 hour. Random migration in the absence of stimulus is indicated (- - -). Data represent mean ± standard deviation (SD) from three independent experiments.