(Gut 2001;49:636-643)

The gram-positive bacterium Listeria monocytogenes causes a life-threatening disease known as listeriosis. The mechanism by which L. monocytogenes invades mammalian cells is not fully understood, but the processes involved may provide targets to prevent and treat listeriosis. Here, for the first time, we have identified the insulin-like growth factor II receptor (IGFIIR; also known as the cation-independent mannose 6-phosphate receptor CI M6PR or CD222) as a novel receptor for binding and invasion of Listeria species. Random peptide phage display was employed to select a peptide sequence by panning with immobilized L. monocytogenes cells; this peptide sequence corresponds to a sequence within the mannose 6-phosphate binding site of the IGFIIR. All Listeria spp. specifically bound the labeled peptide but not a control peptide, which was demonstrated using fluorescence spectrophotometry and fluorescence-activated cell sorting. Further evidence for binding of the receptor by L. monocytogenes and L. innocua was provided by affinity purification of the bovine IGFIIR from fetal calf serum by use of magnetic beads coated with cell preparations of Listeria spp. as affinity matrices. Adherence to and invasion of mammalian cells by L. monocytogenes was significantly inhibited by both the synthetic peptide and mannose 6-phosphate but not by appropriate controls. These observations indicate a role for the IGFIIR in the adherence and invasion of L. monocytogenes of mammalian cells, perhaps in combination with known mechanisms. Ligation of IGFIIR by L. monocytogenes may be a novel mechanism that contributes to the regulation of infectivity, possibly in combination with other mechanisms.The gram-positive bacterium Listeria monocytogenes is a human pathogen that causes listeriosis primarily in immunosuppressed individuals. Symptoms are flu-like, and yet disease may progress to severe complications such as meningitis, septicemia, spontaneous abortion, or listeriosis of the newborn (28,39,83). The number of cases of listeriosis range from 40 to 44 per year in Australia (3, 79) and average 100 per year in the United States (13). Although the incidence of listeriosis is low compared to that of other foodborne diseases, the associated mortality rate is high (approximately 30%) (39, 74, 83). Knowledge of the molecular mechanisms underlying the binding and internalization of Listeria spp. to host cells is limited. New antibiotic, vaccine, and diagnostic targets are needed to prevent and treat infection by Listeria spp., and understanding the processes of adherence and entry into cells is fundamental to defining appropriate preventative and therapeutic strategies.Random peptide phage display has been successfully employed to identify new receptors and receptor ligands (44,52,53,82) and in epitope mapping and mimicking of protein antigens and antibodies (16,42,61) and drug discovery (40,52,78). In this study we employed random peptide phage display in an attempt to identify novel surface antigens that may be used as therapeutic targets ...

Summary. The number of dendritic cells (DC) circulating in the peripheral blood of cancer patients were monitored at multiple time points during chemotherapy and granulocyte colony-stimulating factor (G-CSF) support. DC were identified via the lack of expression of standard lineage markers and high expression of HLA-DR (LN -/DR + ). The expression of DC-associated markers, including CD83, CD11c, IL-3Ra (CDw123) and CD86, within this LN -/DR + population was also monitored. Maximal mobilization occurred during recovery on d 12, with a mean 32-fold increase in LN -/DR + numbers. The most striking increase was observed in the LN -/DR + /CD83 + cell population: 12 d after commencement of treatment, the proportion of these cells had increased by approximately 120-fold when compared with baseline. Peripheral blood mononuclear cell (PBMC) and CD34 + cell numbers also peaked 12 d into the treatment regimen in most patients. These data suggest that it should be possible to acquire substantial numbers of DC from leukapheresis products collected from cancer patients undergoing a standard treatment regimen of chemotherapy and G-CSF. This strategy may be a feasible, low-risk means of acquiring cells for DC-based vaccine studies.