Comparative Metabolism of Guinea Pig Peritoneal Exudate Neutrophils and Eosinophils

In order to gain further insight into eosinophil metabolism, phagocytosis and accompanying metabolic changes were studied in guinea pig peritoneal exudate eosinophils and compared to guinea pig peritoneal exudate neutrophils. Eosinophils and neutrophils ingested lipopoly-saccharide-coated paraffin oil particles in similar amounts, though eosinophils had a more rapid initial ingestion rate. Postphago-cytic hexose monophosphate (HMP) shunt activation was equivalent in eosinophils and neutrophils when 200 latex beads per cell were employed. However, when the particle to cell ratio was increased by reducing the number of cells or increasing the number of latex beads, neutrophils demonstrated a greater ability to respond. When the generation of hydrogen peroxide was studied employing formate oxidation, eosinophils had elevated resting production of hydrogen peroxide. Elevated phagocytosis-induced hydrogen peroxide production by eosinophils was much more evident when the particle to cell ratio was increased by decreasing the number of leukocytes. Thus, the character and extent of the post-phagocytic metabolic burst is highly dependent upon experimental conditions, and comparisons between neutrophils and eosinophils are dependent upon the particular conditions selected. Nonetheless, eosinophils appear to be adapted for elevated production of hydrogen peroxide under both resting and phagocytizing conditions. I thank Dr. Paul Beeson and Dr. Seymour Klebanoff for advice and encouragement. The excellent technical assistance of Peggy Smith and Randy Asplund is gratefully acknowledged.