Chemotaxis of polymorphonuclear leukocytes in response to surface-bound complement-derived chemoattractants generated in situ.

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. Yeast particles that differed in their ability to consume hemolytic complement differed also in their ability to generate chemoattractants. Addition of a complement source to yeast particles able to activate the complement system resulted in a chemotactic response, as well as when fluid-phase attractants were removed prior to the measurement of PMNL chemotaxis, indicating that the chemoattractants generated were absorbed to the surface. Using an immunofluorescence technique, it was found that complement factor 5 coated a circular area around each yeast particle, provided that the particles were able to activate the complement system.