A human myelomonocytic cell line, U937, produced an interleukin-1 (IL-1) receptor antagonist protein (IRAP) which was purified and partially sequenced. A complementary DNA coding for IRAP was cloned and sequenced. The mature translation product of the cDNA has been expressed in Escherichia coli and was an active competitive inhibitor of the binding of IL-1 to the T-cell/fibroblast form of the IL-1 receptor. Recombinant IRAP specifically inhibited IL-1 bioactivity on T cells and endothelial cells in vitro and was a potent inhibitor of IL-1 induced corticosterone production in vivo.

To assess the potential for emergence of resistance during the use of linezolid, we tested 10 clinical isolates of vancomycin-resistant enterococci (VRE) (four Enterococcus faecalis, five Enterococcus faecium, and one Enterococcus gallinarum) as well as a vancomycin-susceptible control (ATCC 29212) strain of E. faecalis. The enterococci were exposed to doubling dilutions of linezolid for 12 passes. After the final passage, the linezolid plate growing VRE contained a higher drug concentration with E. faecalis than with E. faecium. DNA sequencing of the 23S rRNA genes revealed that linezolid resistance in three E. faecalis isolates was associated with a guanine to uracil transversion at bp 2576, while the one E. faecium isolate for which the MIC was 16 g/ml contained a guanine to adenine transition at bp 2505.

Neutrophils contribute to liver damage during endotoxin shock. The objective of this investigation was to document where neutrophils localize in the hepatic vasculature and whether they migrate out of sinusoids or postsinusoidal venules. A well-characterized model of galactosamine and endotoxin shock and immunostaining for neutrophil-associated migration inhibition factor-related protein complex 8/14 S100 calcium-binding proteins were used. Treatment of C3Heb/FeJ mice with 100 micrograms/kg Salmonella abortus equi endotoxin alone or in combination with 700 mg/kg galactosamine induced a time-dependent increase of neutrophil margination in sinusoids and postsinusoidal venules at 4 h. The number of venular neutrophils decreased in both groups at later time points without evidence for transmigration. Extravasation of neutrophils was only observed from sinusoids in galactosamine plus endotoxin-treated animals between 4 and 7 h, which correlated with parenchymal cell injury. After endotoxin alone, large numbers of neutrophils remained sequestered in sinusoids without injury. These data suggest that neutrophils cause hepatocellular injury during endotoxemia after extravasation and are less likely to cause damage when sequestered in the vasculature. In the liver, neutrophils migrate out of sinusoids and not out of postsinusoidal venules.

Previously, a hypomorphic mutation in CD18 was generated by gene targeting, with homozygous mice displaying increased circulating neutrophil counts, defects in the response to chemically induced peritonitis, and delays in transplantation rejection. When this mutation was backcrossed onto the PL/J inbred strain, virtually all homozygous mice developed a chronic inflammatory skin disease with a mean age of onset of 11 weeks after birth. The disease was characterized by erythema, hair loss, and the development of scales and crusts. The histopathology revealed hyperplasia of the epidermis, subcorneal microabscesses, orthohyperkeratosis, parakeratosis, and lymphocyte exocytosis, which are features in common with human psoriasis and other hyperproliferative inflammatory skin disorders. Repetitive cultures failed to demonstrate bacterial or fungal organisms potentially involved in the pathogenesis of this disease, and the dermatitis resolved rapidly after subcutaneous administration of dexamethasone. Homozygous mutant mice on a (PL/J x C57BL/6J)F1 background did not develop the disease and backcross experiments suggest that a small number of genes (perhaps as few as one), in addition to CD18, determine susceptibility to the disorder. This phenotype provides a model for inflammatory skin disorders, may have general relevance to polygenic human inflammatory diseases, and should help to identify genes that interact with the 82 integrins in inflammatory processes.A large number of leukocyte and endothelial cell adhesion molecules are known to play a role in inflammatory processes, leukocyte trafficking, and immune responses (1). The molecules include immunoglobulin family members such as intercellular adhesion molecule 1 (ICAM-1), the selectins, selectin ligands, and leukocyte integrins (1). The P2 leukocyte integrins are heterodimers of CD18 with one of three CD11 subunits:LFA-1 (CD18/CD11a), Mac-1 (CD18/CD11b), and p150/95 (CD18/CD11c). Mutations in CD18 have been reported in humans (2, 3) and in cattle (4, 5) and result in the lifethreatening disorder termed leukocyte adhesion deficiency type I. CD18-deficient patients suffer from recurrent microbial infections, leukocytosis, impaired wound healing, failure of granulocyte -emigration, and lack of pus formation (2, 3). Severe and moderate phenotypes have been described in humans, and the severity of the phenotype appears to correlate with the presence of null or hypomorphic mutations, respectively (3, 6).Previously, a hypomorphic mutation for CD18 was introduced into mice with homozygotes displaying mild leukocytosis, an impaired response to chemically induced peritonitis, and delays in transplantation rejection (7). These mice express a low level of normal CD18 on leukocytes with 2-16% ofThe publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.wild-type levels of CD18 expression on resting or activated leukocytes...

The oxazolidinone linezolid is a new antibacterial approved for marketing in 2000 that inhibits bacterial protein synthesis (5,20,41). It represents a new structural class of antibiotics, with activity against several gram-positive organisms, including several resistant strains. Linezolid has been shown to be effective in treating nosocomial pneumonia caused by methicillinsusceptible and -resistant Staphylococcus aureus or multidrugresistant Streptococcus pneumonia and skin and soft tissue infections caused by methicillin-susceptible and -resistant Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus agalactiae. It is also effective against community-acquired pneumonia caused by methicillin-susceptible S. aureus, multidrug-resistant S. pneumoniae, and vancomycin-resistant Enterococcus faecium infections (15, 31).The oxazolidinones inhibit bacterial protein synthesis, although the exact details concerning the mechanism(s) of inhibition are still emerging. Early results demonstrated that the oxazolidinone eperezolid binds to 50S but not 30S ribosomal subunits. Furthermore, binding was inhibited by chloramphenicol and lincomycin (27). Cross-linking studies have been carried out to identify the sites of oxazolidinone binding. Using ribosomes from Escherichia coli, a number of nucleotide residues in domain V of 23S rRNA were identified, as well as residue A864 of 16S rRNA (28). Colca et al. carried out crosslinking experiments using intact Staphylococcus aureus and showed that tRNA, two ribosomal proteins, and nucleotide A2602 of 23S rRNA all were labeled by the cross-linker (10).The results from mapping oxazolidinone resistance mutations agree with the cross-linking studies. Linezolid-resistant mutants of Halobacterium halobium were isolated and shown to contain single point mutations in the central loop of domain V of 23S rRNA (24). Likewise, Escherichia coli oxazolidinoneresistant mutants contained G2032A and G2447A mutations, which also are in domain V (4, 47