Surgery and the release of a neutrophil Fc γ receptor

The fact that the incidence and mortality from postsurgical sepsis have remained unchanged over the past 15 years raises the possibility that some patients possess an idiosyncratic predisposition to the development of a postoperative sepsis response. Genetic polymorphisms of the neutrophil receptor for immunoglobulin G, CD16, are known, and their inheritance is associated with functional differences in neutrophil phagocytosis. The present studies were designed to provide preliminary data on the effects of surgery on the level of expression of CD16 and its metabolism preparatory to detailed examination of the relationship of these polymorphisms to sepsis responses. Neutrophil CD16 expression was measured by flow cytometry before and after operation in patients undergoing major resectional surgery of the digestive tract. Assays were performed on whole blood preparations as well as on isolated and activated neutrophil preparations from these patients. Neutrophil CD16 expression was constitutively higher both before and after surgery in patients who developed a postoperative sepsis response than in those who did not. Surgery had no effect on the level of surface neutrophil CD16 expression in either group. Surgery depleted intracellular CD16 stores despite the maintenance of a constant level of CD16 on the neutrophil surface, membrane-bound CD16 being more readily cleaved by physiological neutrophil activators after surgery than before surgery. The intrinsic level of expression and postsurgical metabolism of neutrophil CD16 may be an important component of the predisposition of some patients to develop infection or sepsis after injury. Further studies of the distribution of CD16 allotypes and neutrophil function among surgical patients are warranted.