Host defense function in neutrophils from the American bison (Bison bison)

Selected host defense functions of neutrophils isolated from American bison (Bison bison) were characterized and compared with those of cattle (Bos ta urus). Bison neutrophils had a robust chemotactic response to both IL-X and LTB4, with maximal responses occurring at 10(-7) M (IL-X) and 10(-8) M (LT B4). The magnitude of the chemotactic response to IL-8 was similar in bison and bovine neutrophils (except at 10(-7) M IL-8, where bison bad a stronge r response). In response to LTB4, bison neutrophils had a much stronger che motaxis at both 10(-8) and 10(-7) M than did bovine cells. Production of re active oxygen species (ROS) in response to phorbol myristate acetate (PMA) and opsonized zymosan (OpZ) was similar between bison and bovine neutrophil s. However, the production of ROS in bison neutrophils stimulated with OpZ was primarily intracellular, while extracellular release of ROS was evident in bovine neutrophils stimulated with OpZ. Like bovine neutrophils, bison neutrophils did not generate a respiratory burst in response to fMLF. Granu les prepared from bison neutrophils had potent direct killing action on the Gram-negative bacteria Escherichia coli but failed to kill the Gram-positi ve bacteria Staphylococcus aureus and, at intermediate doses, actually had a permissive effect for this bacteria. Thus, bison neutrophils have potent host defense capabilities similar in quality to those of bovine neutrophils ; however, unique differences are present, which may allow bison neutrophil s to respond to the distinct immunological challenges that bison encounter. (C) 2000 Elsevier Science Inc. All rights reserved.