Effects of neutrophil migration inhibitory factors on neonatal neutrophils.

Neonatal neutrophil migration was inhibited by preincubation with a lymphokine/monokine-rich medium conditioned by phytohemagglutinin-stimulated mononuclear leucocytes. Medium conditioned by unstimulated mononuclear cells or nonconditioned medium had no effect on neonatal neutrophil migration. Similar results were obtained with adult neutrophils. Migration distances in the presence and absence of a chemotactic gradient were much lower for neutrophils from neonates than adults when comparing treatments with the corresponding medium, i.e. medium conditioned by phytohemagglutinin-stimulated mononuclear leucocytes, medium conditioned by unstimulated mononuclear leucocytes, or medium unconditioned by mononuclear leucocytes (p less than 0.01). Although locomotion of both neonatal and adult neutrophils was inhibited by treatment, the percent inhibition of random migration was slightly but significantly less for neonates than adults (p less than 0.05). These results demonstrate that neutrophils from neonates are modulated by mononuclear leucocyte-derived mediators.