Neutrophil subpopulations change after thermal injury.

Just as there are subpopulations of mononuclear leukocytes which are functionally distinct, so there appear to be different subpopulations of neutrophils, with different functional abilities. Neutrophils which display the Fc receptor (Fc+) for immunoglobulin have increased chemotactic phagocytic and bactericidal activity compared with neutrophils which are Fc receptor negative (Fc-). To determine if the acquired neutrophil dysfunction which occurs after thermal injury could be due to a change in the percentage of Fc+ neutrophils, serial studies of neutrophil function, including random migration, chemotaxis, phagocytosis, and killing of Staphylococcus aureus, were performed in 12 patients and related to the percentage of neutrophils which possessed the Fc receptor. After thermal injury the percentage of Fc+ cells decreased significantly (p less than 0.01). However, no correlation between the number of rosette-forming cells and random migration (p = 0.48), chemotaxis (p = 0.45), or bactericidal activity (p = 0.50) was found in this patient population. Thus, although thermal injury was associated with a significant decrease in the number of Fc+ neutrophils, this change in neutrophil subpopulation levels did not explain the acquired defect in neutrophil function which occurred after thermal injury.