Cells, phagocytosing

Parr, M.B., et al. 1991. Langherans cells phagocytose vaginal epithelial cells undergoing apoptosis during the murine estrus cycle. Biol Reprod 45 252. 

Eisenbach, M. (2003). Why are sperm cells phagocytosed by leukotytes in the female genital tract Med. Hypoth. 60, 590-592. 

Fig. 2 Pseudocolored SEM images of dendritic cells at low (top) and high (below) magnification, (a) Cells only (b) dendritic cells phagocytosing porous silicon particles and (c) porous silicon particles loaded wifli liposaccharide antigen being taken up by the dendritic cells (Meraz et al. 2012)...

Little information is available about differences in particle uptake as a function of either anatomical location within the lung or as a function of cell type. In the mouse, all types of conducting airway cells, except mucous cells, phagocytosed 5-nm-iron oxide particles administered by inhalation (72,73). The iron oxide particles were translocated through the cell to the interstitium, and this phenomenon appeared to occur primarily in ciliated cells. In human bronchial explants, the ciliated cells took up both asbestos and glass fibers (71), but uptake occurred primarily in areas with relatively few cilia, apparently because areas with numerous actively beating cilia tended to move particles away from the cell surfaces. In hamster tracheal explants, there was a similar effect for long, but not short, fibers of both chrysotile and crocidolite. 

Figure 2. (1) Neutrophils circulating passively in blood capillary. (2) Chemoattractants may be detected by the circulating neutrophils, by the endothelial cells lining the lumen, or both in order that the neutrophils become adhesive. This adhesion is mediated by selectins, a group of cell surface proteins. Neutrophils roll on the surface of the endothelial cells and then actively locomote seeking out spaces between the endothelial cells. (3) The adhesive neutrophils begin to squeeze between endothelial cells. (4) Cells move through the extracellular matrix towards the site of infection. Here adhesion is low and may not be necessary for locomotion. (5) At the site of infection, neutrophils become trapped by increased adhesion where they phagocytose bacteria and liberate the contents of their granules. After Lackie (1982,1986).

Microorganisms are more readily phagocytosed when coated with antibody (opsonized). This is due to the presence on the white blood cells of receptors for the Fc fragment ofIgM and IgG (discussed in Chapter 14). Avoidance of opsonization will clearly enhance the chances of survival of a particular pathogen. A substance called... 

Polymorphonuclear leucocytes (PMNs) employ a system comprising myeloperoxidase, hydrogen peroxide, and a halide factor to kill microorganisms and tumour cells. This process is sometimes loosely called the respiratory burst , which refers to the sudden rise in oxygen consumption by the phagocytosing neutrophils that is independent of the mitochondrial electron transport chain. 

Reticuloendothelial system Cells located throughout the body that can phagocytose particulate matter. 

So far, we have focused mainly on the potential pathways of carotenoid uptake by the RPE from the choroidal blood supply. As mentioned earlier, POS contain lutein and zeaxanthin, and their distal tips are phagocytosed by the RPE. Therefore POS is another source of xanthophylls in the RPE and this pathway of carotenoid delivery and their further fate can be easily tested in cultured RPE. It has been shown that exposure of RPE cells in vitro to HDL stimulates efflux of phospholipids from phagocytosed POS out of the cell (Ishida et al., 2006). Thus it is of interest to determine whether that transport may potentially include xanthophylls and whether other types of lipoproteins may... 

Akagi et al. demonstrated the use of nanoparticles composed of amphiphilic poly (amino acid) derivatives as vaccine delivery and adjuvants [62, 102-104]. To evaluate the uptake of OVA encapsulated within y-PGA-Phe nanoparticles (OVA-NPs) by DCs, murine bone marrow-derived DCs were incubated with 250 nm-sized OVA-NPs for 30 min at 37 °C. The cells were then analyzed by flow cytometry (FCM) and confocal laser scanning microscopy (CLSM). OVA-NPs were efficiently taken up into DCs, whereas the uptake of OVA alone was barely detectable at the same concentration of OVA (Fig. 13). OVA-NPs were more efficiently taken up than OVA alone by DCs, and the uptake of OVA-NPs was inhibited at 4 °C. These results suggest that OVA-NPs were phagocytosed mainly via endocytosis by the DCs. In the case of OVA alone, an approximately 30-fold... 

---