['Toll-like receptors (TLRs) serve as mediators of innate immune responses to pathogen-associated molecular patterns (PAMPs) which include lipopolysaccharide (LPS) and staphylococcal enterotoxin B (SEB). TLR-4 is thought to act as the primary effector of LPS recognition and TLR-2 is thought to mediate responses to Gram-positive bacterial proteins. Chemokines such as macrophage inflammatory protein (MIP-2) are peptides that are responsible for lung neutrophil (PMN) sequestration following an infectious or inflammatory insult. Given the Gram-positive origin of SEB, we hypothesized that mice with altered TLR-4 signaling would exhibit no difference in lung PMN sequestration following SEB when compared to wild-type mice.', 'Wild-type and TLR-4 mutant mice were administered intratracheal saline, LPS (Escherichia coli 0.1 mg/kg), or SEB (1 mg/kg). After 24 h, lung PMN accumulation was determined by myeloperoxidase (MPO) assay and bronchoalveolar lavage fluid cell count (BALfcc). Total lung and BALf MIP-2 was measured by enzyme-linked immunosorbent assay.', 'There was an increase in lung PMN accumulation (by both MPO and BALfcc) and MIP-2 following LPS and SEB in wild-type mice compared to saline-treated controls. In contrast, TLR-4 mice failed to exhibit an increase in lung MIP-2 or PMN accumulation following either LPS or SEB compared to wild-type mice.'] Does toll-like receptor-4 signaling mediate pulmonary neutrophil sequestration in response to gram-positive bacterial enterotoxin?