Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Though ingested Ag are readily degraded into peptides within endocytic vesicles, APC usually cannot present these fragments to CD8 cells. Despite this generalization, some exceptions have been noted. For example, murine macrophage targets readily process heat-killed Listeria monocytogenes (HKLM) into a form recognizable by immune CD8 CTL. Using an assay of Listeria-specific, CD8-mediated cytotoxicity to quantitate Ag presentation by C57Bl/6 macrophage targets, we have examined some of the cellular requirements for this form of Ag processing. To assess whether the physical form of the Ag is an important determinant of processing, we compared the ability of macrophages to present intact HKLM, fractionated L. monocytogenes (LM) membranes, and octyl-beta-d-thioglucopyranoside-solubilized extracts of LM membranes. Macrophages presented each Ag form in a similar manner indicating that processing is not critically dependent on the presence of intact bacteria or even on the introduction of Ag in a particulate form. To gain insight into the metabolic requirements for Ag processing, we examined the effects of several inhibitors. As might be expected, listerial Ag presentation was blocked by brefeldin, a known inhibitor of the endogenous pathway of Ag processing. LM Ag presentation, however, was also blocked by inhibitors of endosomal acidification (chloroquine, ammonium chloride, and monensin) and by the acid protease inhibitor pepstatin A, suggesting that endocytic processing may play an essential role in CD8 recognition of this Ag. To formally establish that this pattern of exogenous Ag processing requires the presence of a class I MHC product, we demonstrated that beta-2 microglobulin-deficient macrophages, which lack class I MHC product expression, cannot present HKLM to CD8 cells. However, we could not block Ag presentation by incubating macrophages with monoclonal anti-H-2K or H-2D antibodies, suggesting that LM Ag presentation may be mediated by some other class I MHC product. Additional characterization of this pathway of Ag presentation is warranted in view of its possible role in initiating CD8-mediated immunity against microbial Ag.
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PMID:Metabolic requirements for macrophage presentation of Listeria monocytogenes to immune CD8 cells. 172 72

The bacteriocin pediocin PA-1 produced by Pediococcus acidilactici PAC 1.0 offers significant potential as a food preservative and as an antimicrobial agent in the medical area. However, low production yields and difficulties in obtaining significant amounts of pure pediocin PA-1 have limited, in part, its biochemical and physical characterization. In the present study, we describe a simple and more efficient purification strategy for pediocin PA-1. A hydrophobic interaction chromatography step using an octyl-Sepharose column was introduced for final purification and polishing. The new method is a scalable one, uses only two steps and yields highly purified pediocin PA-1 with a recovery as high as 73%, which is at least two to three times more than that of the methods reported so far. Highly purified, biologically active pediocin PA-1 of the correct molecular mass (4624 Da, with two disulphide bridges) was obtained. Fourier-transform infrared analysis runs at p2H 6 indicated that pediocin PA-1 was more structured than similar pediocin PA-1 samples purified using the earlier purification scheme.
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PMID:An improved and simplified method for the large-scale purification of pediocin PA-1 produced by Pediococcus acidilactici. 1611 26