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Phagocytosis & Lysosomal Activity Assays

Phagocytosis in mammals serves as an important first line defense mechanism against invading pathogens. It is also essential for continuous clearance of dying cells, tissue remodeling, and acquisition of nutrients for some cells. Phagocytosis is a specific form of endocytosis initiated by recognition and binding of foreign particles by cell surface receptors, followed by their engulfment, and formation of phagosomes. Maturing phagosomes transform to phagolysosomes which destroy the pathogen through enzymes and toxic peroxides.

The endpoint of endocytosis/phagocytosis is eventually degradation of the pathogens' biomolecules in the lysosome. Large particles such as bacteria, cell debris, and aged cells  which have been endocytosed by phagocytotic cells (phagocytosis) are taken up in phagocytic vacuoles (phagosomes), which then fuse with lysosomes, resulting in digestion of their contents. Lysosomes act as the cell's waste disposal system breaking down many biomolecules such as proteins, nucleic acids, lipids and carbohydrates.  
While the extracellular cargo (e.g. nutrients, toxins) binds to the cell membrane and is subsequently transported via endocytosis into membrane-bound endosomes for further degradation by lysosomes, the intracellular components are transported to lysosomes through autophagy, the gradual turnover of the cell’s own components. Again, the resulting vesicles (autophagosomes) then fuse with lysosomes. 
Lysosomes are involved in various cell processes, including homeostasis, cell signalling, energy metabolism, secretion, and membrane repair. Lysosomal dysfunction is associated with many human conditions such as aging, but also with different disorders including cancer, diabetes as well as cardiovascular, neurodegenerative and infectious diseases (reduced lysosomal activity also results in an increase in viral infectivity).

PromoKine’s Phagocytosis Assay Kits utilize pre-labeled E. coli or Zymosan particles as a tool for rapid and accurate detection and quantification of in vitro phagocytosis by fluorescent microscope, spectrophotometer or flow cytometry. Our kits provides a robust screening system for activators and/or inhibitors of phagocytosis and Toll-like Receptor (TLR) ligands.
E. coli and other bacterial strains are often used as a pathogen in phagocytosis assays. Our Phagocytosis Assay Kits (E. coli) utilize heat-killed, red or green-fluorescently pre-labeled E. coli particles.
Zymosan prepared from yeast cell wall (S. cerevisiae) consists of protein-carbohydrate complexes and is frequently used as a pathogen in phagocytosis assays. PromoKine's Phagocytosis Assay Kits (Zymosan) utilize red or green-fluorescently pre-labeled Zymosan particles.

Intracellular of lysosomal activity is quite difficult to measure in living cells. PromoKine's Lysosomal Intracellular Activity Assay Kit uses a proprietary lysosome-specific substrate which has low background fluorescence, high signal-to-background ratio, and is pH insensitive. The self-quenched substrate, which acts as an endocytic cargo, can be taken up by cells and degraded within an endolysosomal vesicle. Degradation of the substrate reverses the quenching and the resulting fluorescent signal that can be measured using a fluorescence microscopy and/or flow cytometry, is directly proportional to the intracellular lysosomal activity.
This kit provides an easy-to-use, sensitive method for imaging and accurate measurement of lysosomal avctivity in cultured cells. The kit includes Cytochalasin D, a cell-permeable inhibitor of endocytosis, that serves as an experimental control.

See also: Autophagy/Cytotoxicity Dual Staining Kit

References, Questions & Answers

Product Name Description Size Catalog Number Information Prices
Phagocytosis Assay Kit (Green E. coli) For rapid and accurate detection and quantification of in vitro phagocytosis by fluorescent microscope, spectrophotometer or flow cytometry. 100 assays PK-CA577-K963 click to select country
Phagocytosis Assay Kit (Red E. coli) For rapid and accurate detection and quantification of in vitro phagocytosis by fluorescent microscope, spectrophotometer or flow cytometry. 100 assays PK-CA577-K964 click to select country
Phagocytosis Assay Kit (Green Zymosan) For rapid and accurate detection and quantification of in vitro phagocytosis by fluorescent microscope, spectrophotometer or flow cytometry. 100 assays PK-CA577-K397 click to select country
Phagocytosis Assay Kit (Red Zymosan) For rapid and accurate detection and quantification of in vitro phagocytosis by fluorescent microscope, spectrophotometer or flow cytometry. 100 assays PK-CA577-K398 click to select country
Lysosomal Intracellular Activity Assay Kit Measurement of intracellular lysosomal activity by flow cytometry and fluorescence microscopy 50 assays PK-CA577-K448 click to select country