Ingestion of hydroxyethyl starch by human leukocytes

Following infusion into animals, hydroxyethyl starch (HES) can be found in nearly all tissues, including phagocytic leukocytes (WBCs) of the reticuloendothelial system (RES). Conceivably, the ingestion of HES molecules by these cells might lead to RES blockade. We studied the ability of WBCs obtained from human blood (neutrophils, mononuclear leukocytes, and mixtures of these cells) and from the RES (alveolar macrophages) to interact with radioactive HES in vitro in the presence of normal serum. In general, 14C-HES failed to associate with blood WBCs (i.e., the cells did not acquire significant amounts of radioactivity). Generally, less than 0.1 percent of radioactivity available in the reaction mixtures became cell associated. Moreover, when used as a phagocytic stimulus, HES elicited practically no superoxide anion production from blood WBCs. Alveolar macrophages acquired significant amounts of 14C-HES (presumably by ingestion). However, only tiny quantities (0.09%) of the total amount of radioactivity available in the reaction mixture became cell associated. Despite this slight interaction with alveolar macrophages, it seems unlikely that the internalization of HES by WBCs will lead to phagocytic dysfunction (such as RES blockade) in humans since human WBCs seem quite limited in their ability to interact with this drug.