The effect of in vivo administration of canine cytokines on neutrophil production and function

The respiratory burst activity (RBA) of canine neutrophils was examined following the in vivo administration of either recombinant canine (rc) granulocyte-macrophage (GM), granulocyte colony-stimulating factor (G-CSF), or normal canine serum. Neutrophils were obtained prior to, during, and following the ten consecutive days of cytokine or serum administration. The RBA was assessed by flow cytometry after either interleukin-8 (IL-8) or phorbol 12-myristate 13-acetate (PMA) stimulation. Neutrophils produced during rcGM-CSF administration were significantly depressed in their RBA when stimulated with either PMA or IL-8. However, the PMA-stimulated RBA of these neutrophils was dependent upon assay duration and protocol. The administration of rcG-CSF produced neutrophils whose RBA was agonist dependent. The RBA of these neutrophils was significantly depressed in response to PMA stimulation but significantly increased following IL-8 stimulation. In this study, the RBA of the neutrophils was cytokine, cytokine-dose, protocol, assay duration and agonist dependent.