IRREVERSIBLE NEUTROPHIL AGGREGATION - A MECHANISM OF DECREASED NEWBORN NEUTROPHIL CHEMOTACTIC RESPONSE

Abstract

To investigate the neutrophil-neutrophil interactions of the [human] newborn for possible clues to the etiology of decresaed newborn neutrophil (PMN) chemotaxis, the authors compared adult and newborn C5a[fragment a of complement component 5]-induced PMN aggregation and chemotaxis at various PMN concentrations. Using Craddock''s technique of C5a-induced aggregation, the newborn lacks the normal biphasic aggregation-deaggregation seen in the adult, suggesting irreversible aggregation similar to that seen when adult PMN are pretreated with cytochalasin-B. Chemotaxis of adult and newborn PMN was studied with a modified Gallin radiolabel technique. A linear correlation between PMN concentration and corrected chemotactic response was found with adult (r2 = 0.93) and newborn (r2 = 0.90) PMN in the range 0.1 .times. 106 to 20 .times. 106 PMN/ml. Random migration was not augmented by increased PMN concentration. The augmentation of newborn PMN chemotaxis was less than that of the adult (adult slope = 2426; newborn slope = 983). Irreversible newborn PMN aggregation may be the underlying event producing decreased PMN chemotaxis and interfering with the normal chemotactic augmentation caused by increased PMN concentration.