Influence of fluid-phase chemoattractants on polymorphonuclear leukocyte chemotaxic responsiveness to a surface-bound attractant.

Polymorphonuclear leukocytes (PMNLs) were allowed to migrate on slides with fixed yeast particles dotted about on the surface. Locomotion was quantified by counting the number of yeast particles in association with a PMNL. Addition of a complement source to yeast particles able to activate the complement system resulted in a chemotactic response even when fluid-phase attractants were removed prior to the measurement of PMNL chemotaxis, indicating that surface-bound attractants guided the PMNLs to the yeast particles. The presence of high concentrations of fluid-phase chemoattractants resulted in a reduced PMNL chemotactic response to the surface-bound gradient. From comparisons between the yeast-slide system and the locomotion-under-agarose assay, it could be concluded that PMNL chemotaxis in response to a surface-bound gradient is less influenced by factor-specific deactivation than the response to a fluid-phase attractant. The PMNL chemotactic response is reduced to both surface-bound and fluid-phase gradients as a result of a non-factor-specific deactivation.